And then the mummies spoke!
Eben van Tonder
8 December 2017

Introduction

It is December and at work, our days changed into a continuum where we are at the factory almost every waking moment.  I am on a quest to find the place where meat curing was discovered and changed into an art.  The journey started when I realised the historic link between meat preservation and mummification or, as it was called years ago, the morbid art of the preservation of corpses.   I learned that the oldest mummies on earth are associated with the two places with the largest natural nitrate deposits on the globe namely the Atacama Desert and the Turfan depression in the Taklamakan Desert in the  Xinjiang region of western China.  Nitrate is, of course, one of the salts that cures meat when it is changed into nitrite through bacterial action and then, chemically, into nitric oxide through various reaction sequences which bring about the curing.  I wondered if meat curing started in one of these places where people could see the power in the soil to preserve flesh the clearest in natural mummification of buried corpses.  Between the two sites, the one in China stood out as the most likely.

At this point, my standard caveat is in order.  I am an entrepreneur who makes my living from the curing industry and is in charge of production at our bacon curing company in Cape Town.  I am not an academic and despite the fact that I studied chemistry, I did not complete my undergraduate work.  As my friends will testify, I am not an expert in matters of archeology, history or the natural sciences.  I do not even claim to be a good meat curer.

What I am, is passionate!  I absolutely LOVE what I do, the world we live in and I LOVE learning!  I learn from the most brilliant people on earth and try to retell their stories in the context of meat curing.  My writing is not so much a thesis as it is a discovery.  After every statement, there always is a question mark.

Here is what I learned so far and the story of how I got to this point.

1.  Salt – 7000 years of meat-curing
2. Nitrate Salts Epic Journey:  From Turfan in China, through Nepal to North India

While there is a debate about the oldest reference to saltpeter and sal ammoniac in India, China, and the West, placing it somewhere in the period after the start of the Christian Era, clear references to saltpeter from Mesopotamia probably date from at least 2000 BCE. Both sal ammoniac and saltpeter were well known to the ancients in these regions with their texts replete with its mention in terms of its medical use, inferences of meat curing and the production of glass and mirrors.  I realised that the origins of the knowledge of these salts were not in China or India as I thought, but from much older civilizations.  While I am very busy at work during the festive season, I patiently wait for several works on Mesopotamian and Akkadian Chemistry I ordered.  The subject never leaves my thoughts and an amazing thing happens.

In the midst of my inquiry, across the vastness of space and time, the mummies who got me on this quest, spoke! Their voices came through the beautifully written June 2002 article by the Canadian journalist, Heather Pringle.  It was again one night when I was unable to sleep when she introduced me to the work of Victor Mair, a professor of Chinese in the department of Asian and Middle Eastern Studies at the University of Pennsylvania.  Here is the link to her full article, Tocharians: The Whites of Ancient China, which is my only reference here.  She tells the story best and a far more rigorous treatment of this subject will follow in subsequent articles.  All quotes are from her article unless I reference my own previous work.

Tocharians: The Whites of Ancient China

Pringle writes that it was on a visit to a small museum in Ürümchi, the capital of China’s remote northwesternmost province, Xinjiang when Mair first came face to face with one of the mummies from the Turfan area.  It was the outstretched body of a man of “just under six feet tall, dressed in an elegantly tailored wool tunic and matching pants, the color of red wine. Covering the man’s legs were striped leggings in riotous shades of yellow, red, and blue, attire so outrageous it could have come straight from the pages of Dr. Seuss. But it was not so much the man’s clothing that first riveted Mair’s attention. It was the face. It was narrow and pale ivory in color, with high cheekbones, full lips, and a long nose. Locks of ginger-colored hair and a graying beard framed the parchment-like skin.  He looked very Caucasian.”

“Local archaeologists had come across the body a few years earlier while excavating in the Tarim Basin, an immense barren of sand and rock in southern Xinjiang.” “The desert at the basin’s heart was one of the most parched places on Earth, and its very name, the Taklamakhan, was popularly said to mean “go in and you won’t come out.””

“The Taklamakan’s merciless climate had one advantage, however. It tended to preserve human bodies. The archaeologists who discovered the stranger in the striped leggings marveled at the state of his cadaver. He looked almost alive. They named him Cherchen Man, after the county in which he was found, and when they set about carbon dating his body, they discovered that he was very, very old. Indeed, the tests showed that he had probably roamed the Tarim Basin as early as the eleventh-century bc. When Mair learned this, he was astonished. If the mummy was indeed European in origin, this would undermine one of the keystones of Chinese history.”

The Question of First Contact

“Scholars had long believed that the first contacts between China and Europe occurred relatively late in world history — sometime shortly after the mid-second century bc when the Chinese emperor Wudi sent an emissary west. According to contemporary texts, Wudi had grown tired of the marauding Huns, a nomadic people whose homeland lay in what is now southwest Mongolia. The Huns were continually raiding the richest villages of his empire, stealing its grain and making off with its women. So Wudi decided to propose a military alliance with a kingdom far to the west, beyond Mongolia, in order to crush a common foe. In 139 bc, the emperor sent one of his attendants, Zhang Qian, on the long trek across Asia. Zhang Qian failed to obtain the alliance his master coveted, but the route he took became part of the legendary Silk Road to Europe. In the years that followed, hundreds of trading caravans and Caucasians plied this route, carrying bundles of ivory, gold, pomegranates, safflowers, jade, furs, porcelain, and silk between Rome and the ancient Chinese capital of Xi’an.”

“Nationalists in China were very fond of this version of history. It strongly suggested that Chinese civilization, which had flowered long before Zhang Qian headed west, must have blossomed in isolation, free of European influence, and it cast early Chinese achievements in a particularly glorious light. In one popular book, The Cradle of the East, Chinese historian Ping-ti Ho proudly claimed that the hallmarks of early Chinese civilization — including the chariot, bronze metallurgy, and a system of writing — were all products of Chinese genius alone. According to Ping-ti Ho, those living in the ancient Celestial Kingdom had never stooped to borrowing the ideas of others and their inventive genius surpassed that of the West.”

“Mair suspected that the Chinese had encountered Westerners from Europe long before the emperor Wudi dreamed up his military alliance. Several early Chinese books, for example, described tall men with green eyes and red hair that resembled the fur of rhesus monkeys. Most scholars dismissed these accounts as legendary, but Mair wasn’t so sure. He thought they were descriptions of Caucasian men. During his studies of Chinese mythology, he had found stories strikingly similar to those in early Greek and Roman tales. The parallels were too frequent to be mere coincidences. And he kept stumbling across words in early Chinese texts that seemed to have been borrowed from ancient languages far to the west. Among these were the words for dog, cow, goose, grape, and wheel. But though Mair repeatedly argued the case for early trade and contact between China and the West, he had no hard archaeological evidence of contact, and no one took him very seriously. “People would laugh at me. I said that East and West were communicating back in the Bronze Age and people just said, ‘Oh yeah? Interesting, but prove it.’ “”

“Never for a moment did Mair expect to find the kind of flesh-and-blood vindication that Cherchen Man promised. Still, he was wary of a hoax. The man’s tailored woolen clothing, with all the complex textile technology it implied, was unlike anything Mair had ever seen from ancient Asia, let alone a remote outpost like Xinjiang. The mummy itself seemed almost too perfectly preserved to be true. “I thought it was part of a wax museum or something, a ploy to get more tourists. How could they have such advanced textile technology three thousand years ago? I couldn’t put it into any historical context. It didn’t make any sense whatsoever.””

“Mair began asking his Chinese colleagues about Cherchen Man. He learned that European scholars had unearthed several similar bodies in the Tarim Basin almost a century before but had regarded them as little more than oddities. In 1895, for example, the British-Hungarian scholar Marc Aurel Stein exhumed a few Caucasian bodies while searching for antiquities and old Central Asian texts in the Tarim Basin. “It was a strange sensation,” noted Stein in his later writings, “to look down on figures which but for the parched skin seemed like those of men asleep.” However, Stein and the Europeans who followed him were far more interested in classical-era ruins than in mummified bodies and failed to investigate further.”

“Early Chinese archaeologists in the region also came across some of the bodies, but they were no more interested than the Europeans. They thought it likely that a few ancient foreigners had strayed into this outlying territory of ancient China by chance. But in the 1970s, while surveying along proposed routes for pipelines and rail lines in Xinjiang, Chinese archaeologists happened upon scores of the parched cadavers, so many that they couldn’t excavate them all. Most of the bodies were very Caucasian-looking — a major discovery that went unreported outside a small circle of archaeologists in China. The mummies had blond, red, or auburn hair. They had deep-set eyes, long noses, thick beards, and tall, often gangly, frames. Some wore woolens of what looked like Celtic plaid and sported strangely familiar forms of Western haberdashery: conical black witches’ hats, tam-o’-shanters, and Robin Hood caps. Others were dressed only in fur moccasins, woolen wraps, and feathered caps, and buried with small baskets of grain. This last group, it transpired, contained the oldest of the Caucasians. According to radiocarbon-dating tests, they roamed the northwestern corner of China in the twenty-first-century bc, the height of the Bronze Age, just as Mair had long been suggesting.”

“Not only had they wandered the Tarim Basin, they had also settled there for a very long time. Cherchen Man had walked the Tarim deserts in the eleventh-century bc, a millennium after the earliest Caucasians. Moreover, murals from the region depict people with fair hair and long noses in the seventh century AD, while some local texts of the same era are inscribed in a lost European language known as Tocharian. If the writers were descendants of the Caucasian-looking people who arrived in Xinjiang nearly 2,800 years earlier, one can only conclude that this was a very successful colony.”

“Convinced now of the authenticity of the mummies, Mair began puzzling over their meaning. Who were these ancient invaders, he wondered, and where exactly had they come from?”

Mair knew that nothing “was ever simple when it came to the Xinjiang mummies. Dead as they had been for thousands of years, they still managed to stir strong feelings among the living. In China, a restive ethnic minority known as the Uyghurs had stepped forward to claim the mummies as their own. Numbering nearly seven million, the Uyghurs viewed the Tarim Basin as their homeland. Largely Muslim, they had become a subjugated people in the late nineteenth century. During the 1930s and 1940s, their leaders managed to found two brief republics that later fell under Chinese control.”

“But Uyghur guerillas continued fighting stubbornly until their last leader was executed in 1961. Since then, the Chinese government has dealt harshly with any sign of separatist sentiment. Amnesty International’s 1999 report for Xinjiang made grim reading. “Scores of Uyghurs, many of them political prisoners, have been sentenced to death and executed in the past two years,” it noted. “Others, including women, are alleged to have been killed by the security forces in circumstances which appear to constitute extra-judicial executions.””

“Still the Uyghurs refused to give up, and when they caught wind of mummies being excavated in the Tarim Basin, they were keenly interested. Historians had long suggested that the Uyghurs were relative latecomers to the region, migrating from the plains of Mongolia less than two thousand years ago. But Uyghur leaders were skeptical. They believed that their farmer ancestors had always lived along the thin but fertile river valleys of the Tarim, and as such they embraced the mummies as their kin — even though many scholars, Mair included, suspected that Uyghur invaders had slaughtered or driven out most of the mummies’ true descendants and assimilated the few that remained. Still, in Xinjiang, Uyghur leaders picked one of the oldest mummies as an emblem of their cause. They named her, with some poetic license, the Beauty of Loulan and began printing posters with her picture. That she was so Caucasian-looking was not a problem in Uyghur eyes: some Uyghurs had Caucasian features. People in Ürümchi, the province’s capital, were captivated. Musicians began writing songs about her that subtly alluded to the separatist cause.”

“This sudden outburst of mummy nationalism alarmed the Chinese government. Before long, everything related to the Xinjiang mummies was considered a matter of state security. No one in government was in any hurry to authorize a genetic test on them. If the mummies’ DNA revealed even a partial link to the Uyghurs — a not unlikely prospect, given the Uyghurs’ mixed heritage — it would further strengthen the separatists’ claims to the region in the eyes of the world. This was something the Chinese wished to avoid, especially after the international condemnation of their treatment of another ethnic minority, in Tibet. Adding to the problem was the Chinese sensitivity to any matter touching on the Tarim Basin. Beyond the wispy river valleys and beneath the Tarim’s bleak desert plains lay immense oil fields. According to Chinese geologists, they contained nearly 18 billion tons of crude, six times more than the known reserves of the United States.”

“Chinese officials were not the only ones worried about genetic testing. Western scholars fretted, too. Some hated the thought that Europeans could have succeeded in planting settlements so far into Asia thousands of years ago. Not only did such a migration threaten the Chinese version of history; it seemed vaguely to smack of ancient colonialism, a notion that many historians abhor. “There’s a lot of Western guilt about imperialism and sensitivity about dominating other people,” said Mair. “It’s a really deep subconscious thing, and there are a lot of people in the West who are hypersensitive about saying our culture is superior in any way, or that our culture gets around or extends itself. So there are people who want to make sure that we don’t make mistakes in our interpretation of the past.””

“Certainly, the presence of ancient Europeans in China — even in its outer reaches — could be twisted and distorted to political ends: people with racial agendas had long been searching for just such evidence.

Ötzi

“As amazed as Mair had been by the mummies back in 1988, he hadn’t had the time to study them. In September 1991, however, he picked up a newspaper and read about the discovery of a frozen, partially preserved corpse of a 5,300-year-old man in a glacier along the Austrian-Italian border. This became Europe’s famous iceman, known as Ötzi.

My own interest in Ötzi is based on the content of what was found in his stomach.  I used the information in my article on the history of meat curing because, in his stomach, the oldest sample of cured meat was found, dating back to 5300 years ago.

The story is that in September 1991, two German hikers from Nuremberg, Helmut and Erika Simon, stumble across the naturally mummified remains of a Copper Age man while wandering through an Alpine glacier at the border between Austria and Italy, on the Austrian-Italian region, in the Ötztal Alps.  What they thought was a hiker who perished recently turned out to be the oldest mummified frozen mummy known today.  He is estimated to have lived in 3,300 BCE and more specifically between 3359 and 3105 BCE.  There is a 66 percent chance that he died between 3239 and 3105 BCE.

The interesting aspect to me is his last meal.  “Researchers thawed his body and have been able to test the contents of his stomach. Mummy specialist Albert Zink from the European Academy of Bolzano said he was able to analyse the nanostructure of meat fibers from a mountain goat found in Ötzi’s stomach – indicating that the meat was raw and had been dry-cured, and not cooked or grilled, which would have weakened the fibers.  He added that Ötzi did not have a proper hunting bow with him, and probably carried the dried meat with him from his home, as raw meat would have quickly gone bad. Further analysis of his stomach contents showed that he had not eaten cheese or dairy products, just meat. “It seems probable that his last meal was very fatty, dried meat – perhaps a type of Stone Age Speck or bacon,” Zink said. As Ötzi had hiked down from the South Tyrolean side of the Alps, it’s likely his provisions came from there.” (The Local)  There is, of course, no way to determine if the meat was cured with salt only or was saltpeter added.

The second interesting fact gleaned from the analysis of his stomick content was where he possibly came from.  “When they tested the contents of his stomach, they found a bacterium called Helicobacter pylori, an age-old pathogen that has evolved into different strains according to the region of the world in which it is found.  About half the people on the planet harbour the bacterium in their stomachs.  It can cause ulcers or gastrointestinal distress and is typically spread among children when they play in the dirt.  While researchers cannot be sure if the Iceman was sick due to the infection, they were intrigued by their analysis of the geographic history of the bacterium.  “Surprisingly, a strain of bacterium in his gut shares ancestry with an Asian strain,” said the study in the US journal Science.  “In contrast to the fact that most modern Europeans harbour a strain ancestral to North African strains.””  (The Local/AFP)  Could it be that he was related to the people who settled in Turpan?

DNA

Mair learned that Austrian scientists planned on performing sophisticated scientific tests, including DNA analysis, on the iceman.   “It occurred to Mair that similar tests on Cherchen Man and his kin could do much to trace the ancestry of the mummies. He immediately wrote to Wang Binghua, one of the foremost archaeologists in Xinjiang, outlining the project that was forming in his mind. He also called Luigi Cavalli-Sforza, a distinguished geneticist at Stanford University who was an expert on ancient DNA. Cavalli-Sforza instantly saw the possibilities. He recommended that Mair contact one of his former students, Paolo Francalacci, at the University of Sassari, in Italy. Mair did just that, and working closely with Wang over the next months he managed to hammer out a deal with the Chinese government. Beijing finally gave the team a green light in 1993.”

“Francalacci thought it best to collect samples from mummies left in the ground, as opposed to bodies already stored in museums. This would reduce the possibility of contamination with modern DNA. So in Ürümchi, he set off, along with Mair and Wang Binghua, for the well-documented grave sites found during the Chinese pipeline and railway surveys of the 1970s and in archaeological studies since. Dozens of these mummies, many lying in relatively shallow underground tombs, had been left alone because of the enormous cost to curate them.”

“At each chosen grave, the young geneticist donned a face mask and a pair of latex gloves, and docked tiny pieces of muscle, skin, and bone from the mummies, often choosing tissue along the inside of the thighs or under the armpits because these regions had been less exposed to the excavators. He sealed each sample in a plastic vial. After several days, he had collected twenty-five specimens from eleven individuals, enough for a modest study. But there was little time for celebration. In a stunning about-face, Chinese authorities suddenly demanded Francalacci’s samples, refusing to allow them out of the country.”

“Then a mysterious thing happened. Just shortly before Mair departed for home, a Chinese colleague turned up with a surreptitious gift. He slipped five of the confiscated, sealed samples into Mair’s pocket. These had come from two mummies. The grateful Mair passed the samples on to Francalacci, who began toiling in Italy to amplify the DNA.”

“For months, the Italian geneticist labored on the mummy samples, trying to extract enough DNA for sequencing. The nucleic acids had badly degraded, but still, Francalacci kept trying various methods, and in 1995 he called Mair with a piece of good news. He had finally retrieved enough DNA to sequence, and his preliminary results were intriguing. The two Xinjiang mummies belonged to the same genetic lineage as most modern-day Swedes, Finns, Tuscans, Corsicans, and Sardinians.”

“The genetic studies were promising, but they only whetted Mair’s curiosity.” “”Everything that I’ve done,” he explained, “even though it’s been running all over the map, it’s all been tied into making things accessible to the everyday guy, the worker. That’s what it’s all about and that’s why I looked at these mummies. They were just everyday guys, not famous people.””

The Textile Connection

“Mair redoubled his efforts to trace the mummies’ ancestry. In Xinjiang, a Chinese colleague had slipped him another parting gift: a swatch of blue, brown, and white cloth taken from a twelfth-century-bc mummy. The fabric looked like a piece of Celtic plaid. Mair passed it over to Irene Good, a textile expert at the University of Pennsylvania Museum. Good examined it under an electron microscope. The style of weave, known as a “two over two” diagonal twill, bore little resemblance to anything woven by Asian weavers of the day. (Indeed, it would be almost another two millennia before women in central China turned out twill cloth on their looms.) But the weave exactly matched cloth found with the bodies of thirteenth-century-bc salt miners in Austria. Like the DNA samples, the mysterious plaid pointed straight towards a European homeland.”

This startled me. The thread that ties it all together is salt and meat curing.  I am not sure what it all means, but this fact is absolutely astounding.  Is it possible that a mummy found in the region which I believe may have been pivotal in spreading nitrate curing of meat across the world may have some direct or indirect link with the Austrian salt mines?  As I was reading the Pringle article, I could hardly contain my excitement.

The Preserving Salts of Turfan

Pringle writes that “excited by the textile connection, Mair organized a new expedition to Xinjiang with Good, her fellow textile expert Elizabeth Barber, and her cultural anthropologist husband, Paul Barber. As the two women pored over the mummies’ clothing, Barber examined the bodies themselves, studying their mummification. Mair hoped this might offer clues to the origins of the people themselves. But the ancient desert dwellers, he discovered, had not taken any of the elaborate measures favored by the Egyptians or other skilled morticians. Instead, they had relied on nature for a few simple tricks. In some cases, family members had buried their dead in salt fields, whose chemistry preserved human flesh like a salted ham. Often, they had arranged the cadaver so that dry air flowed around the extremities, swiftly desiccating the flesh. Cherchen Man, for example, had benefited from both techniques.”

This is exactly the conclusion I assumed the colonists in the Tarim basin would have made.  It is the basis for my assertion and I now believe that nitrate curing was possibly a progression of salt curing, just as nitrite curing is a progression of nitrate curing.  I have described the mechanism and the history of this progression between nitrate and nitrite curing in great detail in my articles Concerning the direct addition of nitrite to curing brine and The Naming of Prague Salt.  That Ötzi man of 3300 BCE could have cured his meat with either salt or salt and a bit of nitrate salt or even ammoniac but I am certain that the people at Turfan cured their meat with sodium nitrate (an assumption based on their use of nitrate salts to preserve the dead).  I now have to compare the dating of these mummies with dates from Mesopotamia where nitrate curing is clearly referred to in ancient texts.

I have described the mechanism whereby salt only cured meat achieves a reddish-purplish cured colour in my article Reaction Sequence under BACTERIAL/ ENZYMATIC CREATION OF CURED COLOUR.  The same progression, I believe, happened in Mesopotamia and possibly in Western Europe.  The question is where did it happen first, here in Tarim or in Mesopotamia or Western Europe and which one was able to impact globally.  Where did the deposits exist in large enough quantity to have precipitated a consistent use which would allow for the development and progression from a curiosity and something that occasionally took place every time one was lucky enough to find nitrate or nitrite as impurities in salt, and where was the deposits consistently high enough in nitrate content to have brought about the development of an art.  In my previous article on the subject, I looked in great detail at the chemical composition of the soil in the basin area.  I quote from my article, Nitrate Salts Epic Journey.

“Nitrate deposits are widely distributed in the Turpan area (Yan Qin, et al, 2012) and the amount of nitrate in the Turpan-Hami basin is estimated at 250 million metric tones which rival those of the famous Atacama nitrate deposits (Wensheng, G. E., et al, 2014).  The most common nitrate deposits are found in the top 50cm of the surface layer towards the center of the basins, particularly in the Turpan basin (this is in contrast to the Atacama deposits which occurs deeper down).  Its origin has conclusively been demonstrated to be from the atmosphere.  (Yan Qin, et al, 2012)

The soil, however, never contains only nitrate.  It is a rich mixture of different minerals and in the Turpan-Hami basin, it is particularly interesting since it contains not only nitrates but a rich mixture of minerals ideally suited for meat preservation.  The soil is a mixture of nitratine, the natural form of sodium nitrate; halite, which is the mineral name for salt or sodium chloride, or rock salt; and mirabilite or Glauber’s salt which is a hydrated form of sodium sulfate.  The nitrate composition ranges from between 2% and 27.98% of the ore tested and average at 10% in the 2012 study by Wensheng, G. E. and coworkers. Halite or sodium chloride was at an average of 30%, darapskite, a crystalized rare mineral which is chemically  a water-containing sodium nitrate sulfate, at 20%, nitratite or sodium nitrate at 10%, and thenardite, an anhydrous sodium sulfate mineral (Na₂SO_4), anhydrite, an anhydrous calcium sulfate mineral, CaSO₄, bassanite, a calcium sulfate mineral with formula CaSO₄·0.5(H₂O) or 2CaSO₄·H₂O, and glauberite, a monoclinic sodium calcium sulfate mineral with the formula Na₂Ca(SO₄)_2, at an average of 3 -8%.  (Wensheng, G. E., et al, 2014).  From these, it is easy to see how, if the rocks containing these minerals were crushed and applied to meat, it acts as a powerful preservative due to the presence of the three key elements used in food preservation to this day namely nitrate, sulphate and chloride.”  What is left for me to do is to find similar analysis of the salts in the deserts in the region where Mesopotamia was located.

Back to the story of the small teams visit to Xinjiang, Pringle writes that “Mair, too, assisted in the work. In his spare time, he translated key Chinese reports on the mummies and published them in his own journal, The Sino-Platonic Papers. This gave Western archaeologists access to the scientific findings for the first time. He wanted to make the mummies the focus of a lively scientific and scholarly investigation. So he set about organizing a major international scientific conference on the mummies, bringing leading archaeologists, anthropologists, linguists, geneticists, geographers, sinologists, historians, ethnologists, climatologists, and metallurgists to the University of Pennsylvania to discuss their ideas. After everyone left, Mair dutifully edited and translated two large volumes of their papers, clarifying their arcane prose until everyone interested in the field could understand it. “If I have grey hair,” he joked, “it was because I was sitting there slaving over this stuff.””

A Western European Colony

“When he had finally finished, he sat down in his office with a pad of paper and a pen. He sifted through hundreds of studies on matters as diverse as linguistics, pottery styles, methods of tomb construction, and metallurgy across Eurasia over the past seven thousand years, searching for cultures whose core technologies and languages bore clear similarities to those of the ancient Caucasian cultures of Xinjiang.  These he recognized as ancestral societies. Slowly, patiently, he worked his way back through time and space, tracing the territories of these ancestral groups. Eventually, after months of work, he sketched a map of what he concluded was their homeland. The territory stretched in a wide swath across central Europe, from northern Denmark to the northwestern shore of the Black Sea. But its heart, some six thousand years ago, lay in what is now southern Germany, northeastern Austria, and a portion of the Czech Republic. “I really felt that that fit the archaeological evidence best,”” Mair later told Pringle it was all beginning to come together.  A clear picture was forming.  The areas described by Mair is the exact location of where my first guess would have been where meat curing originated from, based on everything that I have learned after studying the subject matter for over five years now.

When Mair finally showed his map to some of his colleagues, “though, they were deeply dismayed. Elizabeth Barber, one of his closest collaborators, angrily demanded that he redraw it, insisting that linguistic evidence, particularly the ancestry of ancient words for looms, pointed to a homeland much farther east. Realizing that he had gone too far for the comfort of his colleagues, and that he had yet to find the proof he needed, he bowed to their pressure. He redrew the map, placing the homeland in a broad arc stretching from eastern Ukraine and southern Russia to western Kazakhstan. Then he published it in the conference proceedings. “I thought, for this book, it wouldn’t be too bad,” he confessed, shaking his head. “I decided I wouldn’t go against the flow that much, because that is a big flow with some really smart people.” Then he looked down at the map in front of him. “But in my own integrity and honesty, I’d want to put it in here.” He sketched a narrow oval. Its center fell near the Austrian city of Salzburg.”

All of which brings the story back to Shanghai and “the final arbiter, hopefully, of more DNA testing. Convinced he was right, and desperately wanting to find the proof that would dispel all doubt, Mair believed genetics still offered the best hope of vindication. If DNA testing was sufficient to convict or exonerate men in a court of law, it would surely be strong enough to persuade even the most skeptical of his colleagues. He needed samples for another, more powerful type of DNA testing, but as he had just discovered, the Chinese officials had upped the ante again. Japanese researchers had recently paid $100,000 to acquire samples of the ancient matter for DNA testing, and officials at Shanghai’s Museum of Natural History now wanted a similar sum from Mair.”

“Mair didn’t have it, and he was running out of time. Still, he remained surprisingly upbeat. During a break in the negotiations one afternoon, he invited Pringle to follow Xu Yongqing, the head of the Shanghai Museum of Natural History’s anthropology department, down the stairs to a basement room in the museum. Unlocking the door to a small room behind the employees’ bicycle racks, Xu led the way inside. Along three of the walls, mummies in glass cases reclined luxuriously on red velvet cloth. Stacked three high in spots, they looked much like train passengers bedded down for the night in their berths. Mair stood quietly, scanning the room. Then he saw what he wanted to show me. In one of the lower glass cases, a young woman lay stretched out on her back, stripped of her fine woolens. Her knees were pressed demurely together, her arms rested comfortably at her sides, and her breasts lay round and full, as if she had perished in the midst of nursing a child.”

“But it was the hair that caught my attention. A long wavy golden-brown mane twisted down her back. Standing in that room, I felt an unexpected sense of kinship with her, surrounded as she was by strangers. And I wondered just what had prodded her ancestors to exchange the cool greenness of Europe for the scorching barrens of the Tarim Basin.”

“As always, Mair had some ideas. He believed a new invention had spurred this woman’s forebears to embark on this eastern exodus: horseback riding. Some 5,700 years ago, he explained, Eurasians had begun rounding up wild horses, and sometime later they started sliding bits into their mouths and swinging their bodies onto their backs. These seemingly simple acts led them to conquer terrestrial space. For the first time ever, human beings were able to travel swiftly over immense distances, an accomplishment so exhilarating and adrenalin-charged that they suddenly gave full rein to their wanderlust.”

As I read these comments from Mair I said aloud to myself, “and meat curing!” Two inventions were required for people to travel swiftly over immense distances namely horseback riding and meat curing.  It is difficult for us to comprehend the importance of food preservation in our modern world with a refrigerator in every home.  Governments for centuries before this invention wrestled with the problem.  A prominent write on the subject of food in the 1800’s stated that at one point, every available resource from every government was focussed on solving this one problem.  It may have been at this point when ancients discovered the preserving power of horse sweat on meat.  I explored this in an article earlier this year, Saltpeter, Horse Sweat and Biltong: The origins of our national food.

The curious and gruesome practice starts to make sense when we consider the chemistry and functionality of sweat. Sweat, it turns out, contains nitrite along with rapid nitric oxide production. The nitrite exists as part of the well-known reduction sequence from bacon curing where saltpetre (NO3-) was used and through bacterial action, reduced to nitrite (NO2-). Sweat “contains nitrate in appreciable amounts (secreted by glands) and skin commensal bacteria” which reduce nitrate to nitrite. It has been established that under the right temperature, this reduction step can be achieved in under 4 hours. The mean concentration of nitrate in sweat has been reported to be 2.5 NO3- in day -1 or more. Skin pH is normally between 5 and 6.5. (Weller et al, 1996) This means that skin conditions are “favourable for acidified nitrite” and functionally, the nitrite and NO play and “anti-infectious role.” (L’hirondel, J., 2002: 87)

“So equipped,” Mair went on with growing enthusiasm, “early Europeans had easily spread out across Eurasia, their brisk progress recorded in the ancient campsites they left behind. Some of the invaders swept northward, becoming the Germanic tribes; others journeyed west to become the Celts of the British Isles. But the ancestors of the Xinjiang people had headed east across the grassy steppes of Asia, repelling any who tried to bar their path, and four thousand years ago, a small group of latecomers rode into the vacant river valleys of the Tarim Basin. Finding sufficient land to make a life there, they stayed, passing on their love and knowledge of fine horses to their descendants. When mourners buried Cherchen Man, they arranged a dead horse and a saddle atop his grave, two essential things he would need in the next life.”

“In all likelihood, observed Mair, some of these European invaders rode even further to the east and north, beyond the reach of desiccating deserts. And there they brought with them such new Western inventions as the chariot, a high-performance vehicle designed for warfare and sport, and bronze metallurgy, which made strong weapons that retained their killing edge. Very possibly, a few of these invaders carried with them the secret of writing. While examining the hand of an ancient woman exhumed near Cherchen Man, Mair had noticed row upon row of a strange tattoo along her hand. Shaped like a backward S, it clearly resembled the early Phoenician consonant that gave us our modern S. Mair has also found the identical form of S — which resembles an ancient Chinese character — along with other alphabet form signs, on artifacts of this era from western China.”

Interesting Speculation

As I was driving home from work today, down the N1 highway in Cape Town with the majestic Table Mountain, Lions Head and Devils Peak in the distance, a picture was coming together.  A huge part of this is speculation, but let me paint a possible scenario.

Salt curing was not as prevalent around the world as I thought.  In Sub-Sahara Africa, for example, it was probably never practiced.  In Salzburg, though I suspect it was practiced from very early on.  We know for a fact that it was practiced in ancient Mesopotamia.  Cured meat is the ideal food to take on a long journey into a region that one does not know but preparing the meat takes time, between 5 and 6 weeks if salt only is used.  As we will discuss in a moment, the 5 to 6 weeks is hugely temperature dependent.  This would have been a problem for the traveler or explorer if he had to replenish his food supply.  The discovery of the value of horse sweat for meat curing would no doubt have benefited such explorational travels and migrations immensely.

Ötzi who dies 5300 years ago ate cured meat.  He lived in Asia and was related to the mummies from Turfan and the people who settled in Europe.  This means that meat curing associated with the groups just mentioned predates any mention of meat curing in Mesopotamia.

Nitrate salts were discovered which speeds up the curing of meat.  Salts from certain desert areas contain impurities in the form of these nitrate salts.  The ancients must have noticed that when salt was used with these impurities in them, the meat cured faster.  Curing meat with sodium nitrate can be achieved in one week provided that the meat cut is not too thick.  I suspect that people started using basic crystallization techniques along with simply dissolving the salt and separating out various parts, thus learning exactly which part of the salt is nitrate (saltpeter) and which is ordinary salt.  They would have identified the exact salt responsible for the curing which they called by a particular ancient name.  I, however, question the consistency of the availability of these nitrate salts as well as its purity which would, as ample literature from the 1800’s testifies too, have resulted in very inconsistent and dissatisfactory curing results.

The basis for my questioning of the availability of nitrate salts is that they are highly soluble.  Its solubility is the reason why large-scale natural deposits are restricted to the two driest regions on earth namely the Atacama desert and the Turpan depression.  It easily dissolved in water and is drained deep into the soil.

Another important aspect to consider when curing meat is temperature.  It is important to augment salt and saltpeter with low temperatures in order to prevent the meat from spoiling before it could cure properly.  This is why curing before refrigeration was limited to the colder months of the year.

When migrants arrived in the Turpan basin, they found two salts ideally suited for the traveler namely sodium nitrate and sal ammoniac.  Both occur naturally in this basin and the surrounding hills in appreciable quantities.  Both salts would cure meat much faster than if only salt is used.  Sal ammoniac (ammonium chloride) could have been the answer to the temperature challenge.  The strong endothermic nature of the reaction of sal ammoniac rapidly and significantly reduces the temperature of the meat.  I am convinced that if applied in a container (as is specified for meat curing in ancient Mesopotamian texts), the ammonium chloride will react with the water in the meat and the meat juices and the temperature will be reduced significantly.  This would have been an important technique in managing meat curing with high day-time temperatures and low night-time temperatures.

Since we are so far removed from this time, it is a definite project for me to use ammonium chloride in curing trails to gain practical experience with this salt and the effect on meat temperature at various dosages.  It is a project for the future.  The fact that it is in addition to the temperature benefit, an excellent preservative for meat and that it will definitely cure the meat make this a particularly interesting salt for that time, available in the Tarim basin.

There is little doubt in my mind that the salts would have been traded back to Salzburg and as the availability of these salts improved, curing of meat with nitrate and ammoniac salts would have gained popularity over salt-only curing.  Ancient texts from Mesopotamia talks about the difference in the taste of these salts and there was a preference for saltpeter over sal ammoniac which infers that both were used in food preparation, including meat curing.  I can imagine that it would have been advantageous to take along on a long journey, sal ammoniac over saltpeter due to the greater versatility of the salt in that it also addresses the temperature issue.

Greater availability of these salts and greater purity meant greater experimentation and, I speculate, an art developed.  The art of meat curing.

More Work to Follow

For starters, I need to familiarise myself with Mair’s work following the 2002 article of Heather Pringle.  A clear picture is emerging of boxes that must be ticked in our search for the origins of nitrate curing of meat.  When was nitrate curing possibly discovered in Mesopotamia and how does this relate to the dating of the oldest mummies in Tarim when the colony was started?  When was the colony founded and how do the dates compare?  Is there evidence that the preserving salt of Turfan was ever traded, besides sal ammoniac?  How well established was the trading routes from Turfan into Salzburg between 1000 BCE and 3000 BCE?  Is it possible that the preserving salts of Turfan alerted the ancients to the power of saltpeter only to find local varieties of the same salt in their own backyard?  If sal ammoniac was traded on the scale that we discussed in the previous article, why not the preserving salt of sodium nitrate also or am I right in speculating that they confused the two salts? What methods did the ancients of the 1st and 2nd millennium BCE have to test for sal ammoniac and sodium nitrate or saltpeter?  What is the consistency of the nitrate deposits in the region once called Mesopotamia? How widespread was the collection of nitrate salts and of course, when did domestication of animals start and how easy would it have been to collect nitrate salts from the pens and other animal housings for domestic use?

Conclusion

Without any question, what we know clearer than ever before is that we are, if not in the right place where nitrate curing originated, in one of the most significant locations relative to our quest with ties going back into China, the Mediterranean (through Samarkand) and into the heart of modern-day Europe, to the city of Salzburg.  The epicenter of it all being Turfan.  Is it possible that sodium chloride curing of meat, developed in Salzburg, and the ancients found the preserving salts of Turfan to be the perfect progression to nitrate curing which speeds up the entire process?  Similar to the recent progression of nitrate curing to nitrite curing with the exact same benefit of greater speed and control over the process. I have long ignored Germany/ Austria/ Hungaria/ the Czech Republic, Denmark/ Holland in my search for the origins of nitrate curing after I started to believe that nitrate curing was developed in China, but I have a new project for my German/ Austrian research collaborators centered around Saltzburg.  Is it possible that the tribes in Central Europe were after all the true inventors of the technology or was it, as conventional wisdom teaches Mesopotamia?  Could it have been Turfan?

If nothing else, Turfan is emerging as pivotal in terms of the proliferation of the technology.  Only time will tell how deep the rabbit hole goes!  Into the world of relics, ancient texts, and mummies, ancient chemistry techniques, searching for the birthplace of our trade. There are much more questions than answers, but the two certain things I know besides the fact that Turfan played a key role in the saga is that our trade is ancient, at least 5000 years old!  The other one relates to the mummies. They may be old, but they are not silent!

Restructuring of whole muscle meat with Microbial Transglutaminase – a holistic and collaborative approach.  (30/May/2013)
By:  Eben van Tonder
15 January 2017

Follow up article:  Factors Affecting Colour Development and Binding in a Restructuring System Based on Transglutaminase.

The articles on the complete bacon production system are available in booklet form:    https://tgrestructuringofmeat.pressbooks.com

INDEX

SUMMARY

INTRODUCTION

NATURES BIOLOGICAL GLUE

HOW DOES IT WORK: THE MECHANISM OF GLUING PROTEINS

HISTORY

CHARACTERISTICS OF MICROBIAL TRANSGLUTAMINASE

BENEFITS: SPECIFIC APPLICATIONS

TRANSGLUTAMINASE IN COMBINATION WITH OTHER INGREDIENTS

LEGAL ISSUES

UNRESOLVED MATTERS

CONCLUSION

SELECTION OF PHOTOS 

SUMMARY

Microbial Transglutaminase (MTG) is one of the most important developments in the meat industry, comparable with the direct application of sodium nitrite to curing brines early in the 1900’s. (The Naming of Prague salt)

The meat industry has a long history of restructuring or reshaping large muscles by using various forms of technology such as casings, netting, and ham moulds.  Microbial Transglutaminase (MTG) allows the meat processor the use of a natural process in conjunction with a lightweight mould or grid basket system to re-shape large meat cuts to fit into packaging, high-speed slicers, optimise the use of check weighers, materially improve slicing yields (measured as the percentage of product presented to a slicer that is packed as final product) as well as offers a substantial improvement in overall product quality.

We developed a complete system based on the use of MTG that fits its characteristics and optimises it for both a high throughput factory as well as for small processing operations and optimise the technology in full.

Matters to be considered are the nature of Microbial Transglutaminase (MTG) and its relationship with other functional ingredients, its thermal characteristics, limits on the application, an optimal and flexible process flow, possible negative effects on micro and unforeseen beneficial or negative results.

The focus is on smoked and cured products, even though the application is much wider.  Anybody who is interested in joining this effort or contribute in any way to this work can contact me at ebenvt@gmail.com.

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INTRODUCTION
Transglutaminase functions as a biological glue.  It is important in cell-matrix interaction and the general maintenance of tissue integrity through the creation of isopeptide bonds (inducing the process of cross-linking) between Glutamine and Lysine residues when the protein molecule is enriched with this amino acid.  Extensive work has been done on the benefit of such functionality in the restructuring of meat trim, but few formal studies focused on its benefit of restructuring large muscle pieces such as shoulders or loins.

This is a short summary of the result of our work so far.  Regular updates will be published.  The last date of updating the work will always appear next to the title at the top of the page.

It is instructive to see, in the first place, that the enzyme is widely distributed in nature. It occurs naturally.

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NATURES BIOLOGICAL GLUE

Transglutaminase is an enzyme, involved in many “glueing” activities.  It is present in most animal tissues and body fluids, “and are involved in several biological processes, including blood clotting, wound healing, epidermal keratinization, and stiffening of the erythrocyte (red blood cell) membrane (Aeschlimann and Paulsson 1994). A typical example of a Transglutaminase-catalyzed protein crosslinking reaction is the blood coagulation when a wound heals by something called Factor XIIIa which is an activated form of plasma Transglutaminase.”  (Yokoyama, K., et al..  2004.)

Animal transglutaminases are involved in physiological processes.  Other forms of transglutaminases are found in plants with various types of functioning in one plant or even in one organelle.  Here, enzymes play a role in plants’ processes of growth and development.  One interesting example of a feature of plant transglutaminase enzyme is its sensitivity to light.  This property applies, especially to chloroplast transglutaminase.  (Kieliszek, M and Misiewicz, A.;  2013)

This already points to many possible applications in meat processing such as its involvement in the stabilisation of the muscle matrix and adhesion protein. (Griffin, M., et al.; 2002)  It is widely distributed in nature and should dispell the myth that by using this in meat processing, anything unnatural is being done or used.  This is a natural process.

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HOW DOES IT WORK:  THE MECHANISM OF GLUING PROTEINS

Transglutaminase is an enzyme (in mammals, it is Calcium-dependent) that catalysis several acyl transfer reactions. (Keillor, J. W et al. 2014)  The glutamine residue of a protein acts as the acyl donor and either water or a primary amine (for example Lysine) becomes the acyl acceptor.

Enzymes showing transglutaminase activity is widespread in nature.   Soil bacteria, plants, invertebrates, amphibians, fish and birds. (Griffin, M., et al.,  2002)  Transglutaminase functions as biological glue in two important ways.  On the one hand, it is important in cell-matrix interaction and the general maintenance of tissue integrity through the creation of isopeptide bonds (inducing the process of cross-linking) between Glutamine and Lysine residues when the protein molecule is enriched with this amino acid.  In this case, a primary amine is the acyl acceptor of this amino acid.

The transfer of acyl onto a lysine residue bound in the polypeptide chain induces the process of cross-linking, i.e. the formation of inter- or intramolecular cross-links ε-(γ-Glu)Lys (Kieliszek, M and Misiewicz, A.  2013).

On the other hand, it plays an important role in cell death as it speeds up the chemical reaction (catalyses) of the breakdown of amino acids (deamination) “if there is an absence of free amine groups. In this case, water acts as an acyl acceptor (Motoki and Seguro 1998; Kuraishi et al. 2001). The reactions that are catalysed by this enzyme result in significant changes in the physical and chemical properties of proteins, such as modifications in viscosity, thermal stability, elasticity and resilience of proteins.”  (Kieliszek, M & Misiewicz, A.;  2013)  This will also happen in the presence of excess transglutaminase.

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HISTORY

Clarke et al. introduced the term transglutamine in 1957 to describe the transamidating activity observed in guinea-pig liver. Transamidating is the transferal of an amide group from one compound to another.  Amides (RC(O)NR₂) and esters (RC(O)OR’) are classes of acyl compounds.  (Griffin, M. et al.;  2002)

“Later studies undertaken by Pisano et al., on the stabilization of fibrin monomers during blood clotting, demonstrated that transamidation (transferal of an amide group from one compound to another) is brought about by enzymes which cross-link proteins through an acyl-transfer reaction between the γ-carboxamide group of peptide-bound glutamine and the ε-amino group of peptide-bound lysine, resulting in a ε-(γ-glutamyl)lysine isopeptide bond (Griffin, M. et al.;  2002)

It was known that a similar enzyme plays a role in molding fish protein pasts into Kamaboko, a popular Japanese dish.  A food research group at Ajinomoto Co. “confirmed rapid gelation of several food protein solutions by the enzyme obtained from guinea-pigs liver, which led to the following development of the microbial transglutaminase jointly with Amano Pharmaceutical Company.”  (Fiechter, A.; 2000:  57)

During the 1980’s Yokoyama, Nio and Kikuchi from Ajinomoto were involved “in investigating the feasibility of modifying food protein in industrial applications using the guinea pig liver enzyme and they used whey proteins and actomyosin from beef, pork, chicken or fish as substrates that could be gelled. Subsequently, improvements in the solubility, water-holding capacity and thermal stability of food proteins were demonstrated” (Yokoyama, K., et al.; 2004) which today forms the basis of its application in meat processing.

The use of guinea pig livers was however unacceptable for use in food manufacturing and it hindered its commercialization.  The critical issue was the mass production of transglutaminase.  (Yokoyama, K., et al.; 2004)  Yokoyama, Nio, and Kikuchi from Ajinomoto, in collaboration with Amano Enzyme Co. (Nagoya, Japan) set out to find a constant supply of transglutaminase. In the process, they screened around 5,000 microorganisms for transglutaminase “and identified some microorganisms that produce TGase-like enzymes using the hydroxamate assay (Ando et al. 1989). These microorganisms excreted the enzyme, and one of them produced a high activity. The enzyme in the latter strain was shown to form G-L bonds in proteins, the critical property of a Transglutaminase (Nonaka et al. 1989); it was named microbial transglutaminase (which I abbreviate as MTG), and the source was classified as a variant of S. mobaraensis (Washizu et al. 1994).”  (Yokoyama, K., et al.; 2004)

The enzyme is capable of gelling concentrated solutions of proteins such as soybean protein, milk proteins, and gelatin and myosin of various origins to produce gels with novel physical properties.  The enzyme also causes crosslinking of two or more different proteins to produce new protein conjugates with novel functions.  (Fiechter, A.; 2000:  57)  The same microbial transglutaminase was later isolated in Physarum polycephalum and in Bacillus subtilis spores.  (Kieliszek, M and Misiewicz, A.;  2013)

In mammals, transglutaminase requires Calcium.  “Shimba et al. (2002); Washizu et al. (1994) and Ando et al. (1989) found that transglutaminase isolated from Streptoverticillium mobaraense did not require calcium ions” (Kieliszek, M and Misiewicz, A.;  2013)

The properties of microbial transglutaminase, its ability to cross-link most food proteins, find tremendous application in binding meat together in the process of restructuring.  It is also known to dramatically increases the ability of proteins for emulsification with great impact on the use of soy proteins for example in sausage production.  (Fiechter, A.; 2000:  57)  It improves muscle texture and therefore product quality and assists in the reshaping of large muscles.

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CHARACTERISTICS OF MICROBIAL TRANSGLUTAMINASE

“Microbiological transglutaminase is a single polypeptide with a molecular weight of approx. 38 kDa.  It is composed of 331 amino acids, with an isoelectric point at pH 8.9. It is a simple monomeric protein (not a glycoprotein or lipoprotein).  (Kieliszek, M and Misiewicz, A.;  2013

“A temperature of 40 °C at pH 5.5 is the most favourable for the catalytic activity of transglutaminase, with the exception of transglutaminase isolated from Streptomyces sp., which acts most effectively at a higher temperature of 45 °C. This enzyme is not stable at 50 °C (since it loses 50 % of its activity when heated for 30 min) and is very susceptible to heat in the presence of ethanol.  (Kieliszek, M and Misiewicz, A.;  2013)

Smoking – keep core temperature > 40 deg C and < 50 deg C.

This temperature range is very fortunate for bacon producers since adverse visual changes start happening at around 51 deg C in meat.   The subject of the denaturing of proteins is a bit more complex than one may think.  Generally “thermal denaturation of muscle proteins such as myosin, sarcoplasmic proteins and collagen, and actin, occurs at different temperatures. ”  (KAJITANI, S., et al; 2011)   Due to the importance of this topic, it will be considered in a separate article, attached to this discussion article.

The addition of carbohydrates, such as maltodextrin, saccharose, mannose, trehalose and reduced glutathione (GSH), significantly increases the thermal stability of the enzyme. Casein may protect transglutaminase against degradation by extracellular proteolytic enzymes. At temperatures close to 0 °C, transglutaminase maintains its total enzymatic activity.”  (Kieliszek, M and Misiewicz, A.;  2013)

Micro is key in factory temp.  We can keep it cool!  No problem for TG!

“Enzymes biosynthesised by bacteria are stable at a wide range of pH values, i.e. from 4.5 to 8.0. In addition, they do not require calcium ions to be activated, which is in contrast to transglutaminases of animal origin. This is a highly desirable property, from a practical point of view, for use in enzymatic preparation. The activity of transglutaminase increases in the presence of Co²⁺, Ba²⁺ and K⁺.” (Kieliszek, M and Misiewicz, A.;  2013)  We will exploit this feature by designing a complimentary injection brine.

Microbial transglutaminase is inhibited by Zn²⁺, Cu²⁺, Hg²⁺ and Pb²⁺ ions which bind to the thiol group of cysteine in the active centre.  (Kieliszek, M and Misiewicz, A.;  2013)  We will evaluate the implications by nalizing our water and salt.

Determine through experiment the impact of dissolved potassium chloride on the functionality of TG.

Due to the importance of this topic will be considered in a separate article, “Curing Brine and Microbial Transglutaminase (MTG) – designing the optimal blend”

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BENEFITS: SPECIFIC APPLICATIONS

The application in the meat industry is enormous. Costs are reduced dramatically and quality is improved significantly. In our experience, no single another technology offers this level of positive impact both for the producer and the consumer.

In terms of whole muscle meat, the application is to reshape it into a regular structure.

It is very important to understand that reshaping does not only involve MTG, but critically, also a ridged structure to create the shape and freezing.  The shapes are created in this system through the use of specially designed lightweight grid baskets by an engineering company.  Design considerations were ease of handling, efficiency, and cost.

The five areas where processors report the most pronounced benefits from the total system are:

1. Slicing yields

At our own plant slicing yields with the use of this system is between 90% and 95%. It has been reported in private communication from other production managers, that they regularly achieve slicing yields of 98% by a consistent application of this overall system.

2. Production yields

A reduction of losses during thermal processing.  When we do not use this system, losses during smoking is between 8% and 12%, depending on the meat quality, the cut, the initial injection rate and tumbling time.  When the system is used, with all other factors remaining the same, moisture loss during smoking is reduced to between 2.5% and 5%.

3. Improved product quality

Product quality improves materially in terms of juiciness, overall texture, and colour development.  Catering and food services clients add the benefit of consistent product portioning.

These changes are attributed to a variety of factors in combination.  Pressure is added to the meat when they are places in the grids baskets.  The effect of such pressure is the current subject of several studies and seems to be playing a bigger role than originally thought.

A second reason is the effect of MTG.  A third reason is that a specially coated, smoke-permeable paper is wrapped around the meat cut before it is placed inside the grid basket.  This retards the unnecessary loss of moisture, especially at the meat surface during thermal processing and it distributes the heat better.

The orientation of the meat during thermal processing plays a huge roll.  Traditionally such cuts are hung on smoker trolleys which favour the release of moisture due to the pressure matrix that develops inside the muscles.  Laying the meat down in a trolly materially alters this pressure matrix and substantially reduce unnecessary moisture loss which impacts both production cost and product quality.

What is the exact contribution of each of these factors in isolation?  How can ham technology be incorporated into bacon production?

4. New products

For the producer, Transglutaminase further allows for the utilisation meat offcuts and by-products, such as collagen, blood proteins and mechanically deboned meat, in manufacturing meat products with a higher nutritive value by supplementing it with amino acids in which it is deficient (e.g. exogenous lysine). (Kieliszek, M and Misiewicz, A.;  2013) Ultimately the consumer wins through the lower price point of these products. Generally, opportunities exist in the production of fine and coarse-minced sausages, Vienna sausages and smoked meat. Instead of high-quality meat, lower quality raw materials and additives, such as skimmed milk powder, soy or wheat flour, can now be used to manufacture products. (Kieliszek, M and Misiewicz, A.;  2013)

5.  R&D component

In the work that we do here, a very strong R&D component comes with the Grid system, the Transglutaminase and how the entire process is put together.  Finding new and innovative ways of exploiting any new system is of tremendous benefit. Networking makes this task easy and this brings to the fore the power of this forum.

I report on these “war stories” in Applications and Clever Ideas

The overall system as utilised in our facility is the following.

System:  Inject with a multi-needle injector -> tumble under vacuum -> fill into lightweight, specially designed moulds or grids -> thermal treat/ smoke -> chill -> freeze -> slice.  Sanitise – repeat.

System benefits:  Ensure  *  ease of handling both filling and closing the lid without specialised equipment needed; * effective for small processors and large plants; * modular.

Filling the grids:  A simple system has been designed to facilitate filling the grids.

The features and benefits of the system are in our view unparalleled in terms of recent developments in food science.

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TRANSGLUTAMINASE IN COMBINATION WITH OTHER INGREDIENTS

We evaluate the composition of a mix of ingredients that complements transglutaminase applied in a meat processing and curing environment.  The enzyme is required in very small quantities in meat processing.  Experience has shown that it is best used along with a carrier that makes it more manageable as an ingredient on its own.  Secondly, when you are binding meat together with TG, then you need a connective protein.

Meat – Protein – Meat

Let’s look at some options.

GELATIN OR COLLAGEN

The first such ingredient is gelatin or collagen which is a such a connective protein.  It is a structural protein that imparts rigidity.  It is made up of amino acids which comprise approximately 30% of the proteins within the body.  They represent rigid structures, found in bones, tendons, and ligaments.  In the skin, it provides firmness, suppleness and constant renewal of skin cells. It is responsible for skin elasticity.  (Dr Ananya Mandal)

Gelatin is the heat-denatured, partially hydrolyzed form of native, insoluble collagen.  The temperature at which the collagen protein unfolds (denature) depends on the species and hydroxyproline content.  The unraveling of the collagen protein results in a viscous colloidal solution of gelatin. (Tarté, R.; 2009:  152)

Gelatin is in the first place a “thickening agent” with very good thermal stability.  Its value in meat processing where primals are injected is in the first place not in its ability to form cross-links through transglutaminase, but to thicken inside the meat before the enzyme had a chance to create the cross-links and as a result of this, to minimize syneresis of the injection brine after the tumbling phase under vacuum.

Gelatin is the ideal thickening agent to accompany transglutaminase since it contains a variety of different amino acids, including our old friends Glutamine and Lysine which are now cross-linked by the action of transglutaminase.  (Aguilar, M. R. and Román, J. S.; 2014:  186)  It is important to use the right kind of gelatin.  Fish and pork gelatin will be objectionable for either religious or allergen concerns by various processors in various parts of the world and it is an important consideration.

Why will collagen be preferred in certain conditions as opposed to gelatin in others?  Which condition will favour which application?

Is there a way to ensure maximum “retention” of TG within the meat matrix.

I.e. purge after tumbling may reduce the efficacy of the TG.  What hydrocolloids can possibly perform better in conjunction with a connective protein?

I recently learned about new technology that facilitates cold gelling when the brine enters the meat matrix.  How can this be used in combination to achieve greater retention of brine after tumbling and, at the same time, works well in combination with TG and collagen?

The second functional ingredient that becomes important in administering transglutaminase is polyphosphate.

PHOSPHATES IN THE BRINE

(point to be re-visited in its entirety)

Adding phosphates to the transglutaminase/ gelatin mix raises the pH of the solution so that transglutaminase does not begin to set while in solution.  As soon as the mix touches the substrate of the meat, the pH is lowered and the enzyme becomes active.  Phosphates are, however, not the only way that this can be achieved and a new formulation is currently being designed and tested by myself and various collaborators which will exploit other systems to achieve the same results.  The goal in this particular work is to design a phosphate free brine to be used in conjunction with the MTG.

Due to the importance of this topic will be considered in a separate article, “Curing Brine and Microbial Transglutaminase (MTG) – designing the optimal blend”

INJECTION BRINE

From the perspective of MTG, it is useful to add a small amount of potassium salt to the brine mix.  There is an opportunity to re-design the brine system.

Due to the importance of this topic will be considered in a separate article, “Curing Brine and Microbial Transglutaminase (MTG) – designing the optimal blend”

MALTODEXTRIN

A further important ingredient is maltodextrin.

Maltodextrin is a bulking agent produced from starch and consists of beta-D-glucose.  (Kerry, P. and Kerry, J. F.; 2011: 262)  “Glycerol, maltodextrin, sorbitol, and xylitol are often used to preserve proteins and enzymes.”  “Glycerol and maltodextrin have long been regarded as proteins stabiliser or additives which have the ability to affect the equilibrium between the nature and the unfolded conformational state of the enzymes.

Moreover, glycerol and maltodextrin can evidently increase the viscosity of the enzyme solution, which may cause reduction of chemical or biological reaction rate which could result in inactivation of the enzymes.”  (Bourneow, C., et al. 2012)  An addition to these, it is the “carrier” for transglutaminase.  (Kerry, P. and Kerry, J. F.; 2011: 262)  It prevents clotting up of the ingredient mix.

There are other “ingredients” that comes from processing steps.

VACUUM TUMBLING

Vacuum tumbling is very important means of getting rid of air bubbles that result from mixing the solution. The surface tension of the bubbles interferes with the formation of the chemical bonds.  Extracting air bubbles from the solution and the meat is important for adhesion.

TIME

It is has been suggested by some that the minimum time required for the formation of bonds is anywhere from 4 to 6 hours.

In reality, it has been shown that effective bonds from as low as three hours. More formal work on this is currently being undertaken.

PH AND TEMPERATURE

When activity is measured using synthetic substrates, Transglutaminase shows high activity in a wide pH-range, i. e. between pH-value 5 and 8. Keep the temperature between 40 and 50 deg C.  For a curing and smoking processor, the denaturing of various proteins at different temperatures are important considerations from a perspective of overall colour development. It has been shown by ourselves that an internal core temperature of between 35 and 45 is sufficient to achieve more than adequate binding.  This range is important since visual denaturing and a “paling effect” starts taking place from a core temperature of 51 deg C.

FREEZING

It has been found that a slightly longer time is required for freezing meat that has been processed in the overall system.  The exact reasons for this are currently the subject of separate studies and will be reported on soon.  Several production managers have however been interviewed and the consensus is that this increase in freezing time is marginal and is easily accommodated within current processing environment.

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LEGAL ISSUES

MTG is classified as a processing aid and no labelling requirements apply to its use.  This is in contrast with the use of alginate, for example.  (This section to be expanded with the exact US, Canadian, EU, Chinese, Australian, New Zealand, South African, Korean and WHO classification of MTG with all legal considerations listed).

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UNRESOLVED MATTERS

What is the effect of the use of transglutaminase on the overall meat environment as it affects microbial activity?  Generally, our goals and priority’s are:

Achieving water salt phase of 20% or more (as it related to the moisture content in the formula (% NaCl x 100/ (% + moisture) = %);  Much work on this still remains, especially in a reduced sodium environment.  As I have mentioned already, focused development work is underway by myself on this and results will be made available very soon.

What exactly is the water salt phase %?

Water activity

 Maintaining brine to meat ratio that will maximise anti-microbial and anti-botulinal efficacy.  Meat to brine ratios of up to 20% brine to 80% meat has been used without the need for any other functionals besides sodium nitrite, sodium ascorbate or erythorbate and phosphates.

What exactly is the water activity?

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CONCLUSION

One talks about a “game changer.”  The discovery and commercialization of microbial transglutaminase are such a “game changer.”  It is the biggest event in meat processing since Ladislav NACHMÜLLNER invented the first sodium nitrite curing brine at the beginning of the 1900’s.  Over the next 50 years, it will completely transform every meat processing practice.

A multi-disciplinary approach has by far the biggest advantages in re-structuring whole muscle meats using MTG.  In our experience, development work of this nature is best performed in an open forum where multiple individuals and organisations contribute to the benefit of the consumers at large.

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SELECTION OF PHOTOS AND CLIPS

A few photos from our factory.

Remember to also look at the follow-up article:

Factors Affecting Colour Development and Binding in a Restructuring System Based on Transglutaminase.

(c) Eben van Tonder/ ebenvt@gmail.com

References

Aguilar, M. R. and Román, J. S..  2014.  Smart Polymers and their Applications.  Woodhead Publishing.

Bourneow, C. , Benjakul, S. and H-Kittikun, A..  2012.  Impact of some additives on the stability of microbial transglutaminase from Providencia sp. C1112.  As. J. Food Ag-Ind. 2012, 5(03), 226-233

Fiechter, A..  2000.  History of Modern Biotechnology I.  Springer.

Griffin, M., Casadio, R., Bergamini, C. M..  2002. Transglutaminases: Nature’s biological glues.  Biochem. J. (2002) 368, 377–396 (Printed in Great Britain)

KAJITANI, S., FUKUOKA, M, SAKAI, N.  2011.  Kinetics of Thermal Denaturation of Protein in Cured Pork Meat.  Japan Journal of Food Engineering, Vol. 12, No. 1, pp. 19 – 26, Mar. 2011

Karayannakidis, P. D., Zotos, A., Petridis, D., Taylor, K. D. A.  2014.   The Effect of Washing, Microbial Transglutaminase, Salts and Starch Addition on the Functional Properties of Sardine (Sardina Pilchardus) Kamaboko Gels.  Journal Citation Reports® (Thomson Reuters, 2015)

Kerry, P. and Kerry, J. F..  2011.  Processed Meats: Improving Safety, Nutrition and Quality.  Woodhead Publishing.

Keillor, J. W., Clouthier, C. M., Apperley, K. Y. P, Akbar, A., Mulani A..  2014.   Acyl transfer mechanisms of tissue transglutaminase.  Bioorganic Chemistry Volume 57, December 2014, Pages 186–197

Kieliszek, M and Misiewicz, A.  2013.  Microbial transglutaminase and its application in the food industry. A review.  Folia Microbiol (Praha). 2014; 59(3): 241–250. Published online 2013 Nov 8. 10.1007/s12223-013-0287-x

Dr Ananya Mandal, MD.  What is Collagen? (http://www.news-medical.net/health/What-is-Collagen.aspx)

Tarté, R..  2009.  Ingredients in Meat Products: Properties, Functionality and Applications.  Springer.

Yokoyama, K., Nio, N., Kikuchi, Y..  2004. Properties and applications of microbial transglutaminase.  Received: 22 August 2003 / Revised: 1 December 2003 / Accepted: 5 December 2003 / Published online: 22 January 2004; Springer-Verlag

Photo Credits:

All photo’s from http://www.ajinomoto.com/en/aboutus/history/chronology/

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Bacon Curing - A Historical Review
Eben van Tonder
Original Article: 31 May 2016
Update: 25 January 2023

Also, see Bacon & the Art of Living, Chapter 15.10: Meat Curing – A Review

Introduction

Meat curing has been and remains one of the important industries on earth. Not much has been done to trace its origins from antiquity or to chronicle the developments of the last few hundred years. With the blog, The Earthworm Express, I seek to rectify this in terms of the meat industry in general. Understanding the history of a process enables us to understand our current work better. In relation to meat curing, I transformed the articles dealing with this into chapters for my book on the history of bacon or meat curing. It is the first such attempt I am aware of where a serious effort is made to follow all the salient developments related to curing over centuries and even millennia. I place it within the narrative of friends setting up a bacon company during the closing years of the 1800s and the opening decades of the 1900s. Some may find this format irritating, but it was done in an effort to make the work accessible, and, along with the history of meat curing, dwells on the development of the meat trade generally. I cannot help to add a sizable volume of work to the quest of finding purpose in life as meat curing is an all-consuming passion of my life, and it is not possible to deal with the subject matter and not with life that is as rich and full as the subject matter at hand. The book is Bacon & the Art of Living and is available online.

The Curing Process

A modern understanding of the benefits of curing is that it fixes a pinkish-reddish cured meat colour. It endows the meat with unique longevity, even if left outside a refrigerator, many times longer than that of fresh meat. It is powerful enough to prevent the deadly toxin formation by Clostridium botulinum. It prevents the formation of rancidity in fat. It lastly gives meat a unique cured taste.

What is completely mesmerising in meat curing is that the basic process follows physiological processes essential for human life. The fact that humans stuck, as it were, to the evolutionary playbook in its practice of curing in that it mimics these physiological processes to the smallest details is completely astounding! I will write to you separately about how the basic processes in curing are exactly the processes essential for life that happen every moment in our bodies! Far from a villain that causes health trouble, nitrate, nitrite, and nitric oxide are indispensable molecules to life on earth. Of course, its overuse, in proportions greater than what nature dictates, is extremely unhealthy, as we discussed in Chapter 12.06: Regulations of Nitrate and Nitrite post-1920: the problem of residual nitrite. By and large, meat curing is a safe and essential technique for preserving meat.

Discovering the mechanics behind meat curing was a slow process that took hundreds of years. (For an overview of some of the people behind the most important discoveries, see The Fathers of Meat Curing.)  A survey of farm curing methods conducted in 1951 by the US Department of Agriculture among farmers in the US revealed the following brining methods used:

• Dry cure – no pumping,
• Brine cure – no pumping (the use of cover brine),
• Brine cure – pumped, and
• Dry cure – pumped.  (Dunker and Hankins; 1951: 4)

We can add the following to this list from 1951.

• Sweet Curing (Stitch Pumping with dry curing and with hot smoking)
• Mild Curing (the re-use of cover brine with or without stitch pumping, with or without dry salting)
• Pale Dry Bacon (Sweet curing with no smoking, only drying)
• The direct use of nitrites in curing brines
• Grid or Formed Bacon

For a discussion on the mechanics of curing, please review The Curing Reaction.

Salt Only (Dry cure – no pumping – salt only – using a dry rub or brine)

Exactly where salt curing of meat started is an interesting question. There is ample evidence that salt preservation of meat was done from the earliest of times. Despite the fact that there are records of fish being salt-cured in China going back to 2000 BCE and from Egypt and Mesopotamia, the practice is much older.

Ancients consumed their food raw before it was discovered how to make fire. (How did Ancient Humans Preserve Food?) Even after fire-making was invented and this technology became universally part of human culture, humans only cooked their food intermittently for a very long time. There are cultures to this day that eat raw meat in one form or the other. Besides this, hanging meat to dry in the sun, the wind, or over a fireplace without adding any curing agent such as salt was practiced in southern Africa, North America, and Nepal, to mention just a few places that I am personally aware of. It was likely universally practiced at some point in the past. 

Salt was without question the first curing agent and in all likelihood, salt in the form of seawater. It seems that as people migrated from coastal regions, inland, they developed solar evaporation to extract the salt from seawater along with techniques such as boiling the water off when it became more difficult to access seawater when communities started to settle further away from the coast. It is often claimed that salt did not play a significant role in southern Africa. Nothing could be further from the truth! After a careful investigation of the use of salt for meat preservation in southern Africa, the evidence points to the fact that the power of salt to preserve meat was known by for example the Khoe and the San people, but they preferred to hang meat in the sun and the wind to dry. Still, salt played a significant role in the diets of ordinary people. They understood it and used it!  (Salt and the Ancient People of Southern Africa) A direct link can be made to every great civilization that existed in antiquity in the fact that they all knew the value and uses of salt.

China

One of the greatest and oldest civilisations that ever existed (and still exists) is the Chinese! What we know for sure is that salt curing of meat occurred in China from very early on. Flad, et al. (2005) showed that salt production was taking place in China on an industrial scale as early as the first millennium BCE at Zhongba. “Zhongba is located in the Zhong Xian County, Chongqing Municipality, approximately 200km down-river along the Yangzi from Chongqing City in central China. Researchers concluded that “the homogeneity of the ceramic assemblage” found at this site “suggests that salt production may already have been significant in this area throughout the second millennium B.C..” Significantly, “the Zhongba data represent the oldest confirmed example of pottery-based salt production yet found in China.”  (Flad, et al.; 2005)

Salt-cured Chinese hams have been in production since the Tang Dynasty (618-907AD). First records appeared in the book Supplement to Chinese Materia Medica by Tang Dynasty doctor Chen Zangqi, who claimed ham from Jinhua was the best. Pork legs were commonly salted by soldiers in Jinhua to take on long journeys during wartime, and it was imperial scholar Zong Ze who introduced it to Song Dynasty Emperor Gaozong. Gaozong was so enamoured with the ham’s intense flavour and red colour he named it huo tui, or ‘fire leg’. (SBS) An earlier record of ham than Jinhua-ham is Anfu ham from the Qin dynasty (221 to 206 BCE).

In the middle ages, Marco Polo is said to have encountered salt curing of hams in China on his presumed 13th-century trip. Impressed with the culture and customs he saw, he claims that he returned to Venice with Chinese porcelain, paper money, spices, and silks to introduce to his home country. Polo alleges that it was from his time in Jinhua, a city in eastern Zheijiang province, where he found salt-cured ham. Marco Polo is a controversial figure in that there is great uncertainty if he ever actually undertook the voyages he wrote about. Still, these stories, either first hand from Polo or from someone else who compiled it, the reports certainly had a basis in reality.

The reach of Chinese technology for salt production was impressive. On a trip to New Zealand, I learned that the Māori never developed salt extraction in any form. I did a short review of the colonization of Indonesia and salt extraction technology in an article, “Concerning the lack of salt industry in pre-European New Zealand and other tales from Polynesia and the region.” A brief survey of the history of salt extraction from Fiji, Samoa, New Guinea, Vanuatu, and Taiwan shows the large influence of China on regional salt production technology.

This study also revealed a possible forerunner of more formal salt production around the world, including in China. One of the earliest ways that salt found itself in food preparations was undoubtedly through the fact that seafood was consumed that naturally had added salt which came from the water. Another way would have been if meat was stored in seawater. Immersing carcasses of animals and fish in water would have been one of the earliest forms of preservation and since earliest communities gravitated to coastal regions, salt water would have been used and in addition to seafood which is rich in salt, it would have entered early human culture when food was cooked in seawater. It is likely that carcasses were stored in water at first to hide them from predators and its preserving power would soon have been discovered. Migrating groups would have noticed how seawater preserved meat better and changed (improved) the taste of the meat.

Polynesia

The study of salt in Polynesia shows that as groups migrated inland, away from the sea, saltwater was boiled to evaporate the water and leave the salt as a very basic salt extraction technique. The salt was then traded with the inland communities. This was widely practised in Taiwan until fairly recently. The references to it in Polynesia and Asia offer a suggested progression of the extraction of salt from seawater. Studies from Fiji identified population size, even of coastal communities to be a key driver of salt extraction technology. 

It seems that migrants from Taiwan spread their technology throughout the lands of Polynesia. Every evaluation of salt on the islands I looked at supports this. China would undoubtedly have been a key driver in the region in progressing salt extraction technology with Pappa New Guinea playing a large role where a multitude of techniques to extract salt was (and still is) in use. Solar evaporation of seawater, extracting salt through plant material, and burning plants, naturally high in salt are a few of the developments from the region, which all presumably have their roots in the practice of simply boiling seawater; in turn, this was probably a progression of the practice of cooking food in seawater; which, in turn, had its roots in storing meat in saline solutions; which had its roots in simply immersing carcasses in bodies of water for storage. When we are at this point, we are clearly at the very early age of the existence of cognitive modern humans who were cognitively similar to modern humans.

New Zealand

In a discussion with a curator from the Canterbury Museum about the matter of salt production and trade in salt being absent from New Zealand’s ancient history, he drew my attention to the interesting practice of the Maori to slow boil large quantities of shellfish in freshwater. Had they not done so, it would not have been possible to consume large quantities at a time. There seems to be evidence that they did, in fact, consume large quantities of this at a time. It supports the notion that they knew about salt and the possibility exists that this was true across the world from very early. Like the people of southern Africa, people probably knew at least some of the techniques for extracting it, but some local populations, as was the case in New Zealand and many of the southern African populations, may have opted not to use the technology simply because it was not necessary. In the case of the Maori, they definitely knew to remove some of the salt from shellfish before consuming it. They have a word for salt which shows that they definitely knew about its taste. In southern Africa, most would have gotten their salt from meat or milk and when they could only eat plant material, they knew that a bit of salt would cure the ailments which resulted from a lack of salt.

Salt as a condiment

One can not talk about salt curing and not at least make mention of its use as a condiment. Even though too much salt alters the taste negatively, preservation through salt and altering (enhancing) the taste go hand in hand. Evidence is emerging about the use of condiments in food, the earliest discovery so far which dates in Europe going back 6000 years ago in Germany and Denmark. Archaeology magazine (Nov/ Dec 2013) reports that “a team of researchers has found phytoliths, small bits of silica that form in the tissues of some plants, from garlic mustard seeds, which carry strong, peppery flavour but little nutritional value. Because they were found alongside residues of meat and fish, the seed remnants represent the earliest known direct evidence of spicing in European cuisine. According to researcher Hayley Saul of the University of York, “It certainly contributes important information about the prehistoric roots of this practice, which eventually culminated in globally significant processes and events.” (Archeology)  Salt would undoubtedly have been part of their arsenal of taste enhancers.

It seems that our relationship with salt has never been static and to this day, it continues to evolve. More importantly, the discoveries in Denmark and Germany brings into focus innovations in the European lands of Germany, Austria, Hungary, the Czech Republic, Switzerland, Denmark, Holland, Belgium, Spain, France, and Poland. Besides these, there is Irland. What was happening in these regions while cities and kingdoms covering Mesopotamia, India, Pakistan, and Nepal were developing salt industries and very sophisticated meat-curing technologies based on salt, nitrate, and sal ammoniac? I am filling in the gaps over the years to come.

The Mechanism of Salt-Curing

For years I never seriously looked at salt-only-curing. Yes, its mechanism is well known, or so I thought! The salt reduced the water in the meat which retards the micro activity and meat breakdown (enzymatic) while L-Arginine slowly oxidises to L-citrulline and nitric oxide and nitric oxide cures the meat.

The booklet that Edward De Bruin, my South African friend living in New Zealand, sent me (Methods of Meat Curing, 1951, US Dep of Agriculture) reported that in a survey done in the early 1950s, it was found that 37 percent of the farmers used dry curing. The curing agent they used was salt only. The author describes it as follows, “a fine grade of sack salt or table salt applied to hams, shoulders, and bacons. All the salt was applied at one time by about one-half of the farmers, 10 pounds (4.5kg) of dry salt per 100 pounds (45kg) of meat being used. The liquid extracted from the meat during cure was not permitted to accumulate. Curing temperatures ranged from 20° to 50° F. (-6°C to 10°C), the average being about 40°F (4°C). Most hams weighed 20lb (20kg), 25lb (11kg), or 30lb (13.6kg) : shoulders and bacons weighed 20lb (20kg) pounds. The hams were cured for 1½ days per pound : shoulders and bacons, 1¾ days. About 50 percent of the farmers smoked their meat. Prior to smoking 3 to 1 days in hickory smoke, the meat was washed. The meat was stored in a dry, cool room with some air circulation. Consumption began immediately after the meat was cured and smoked, although some meat was stored for 9 months.”

The method was simple and effective. It took around 30 days to cure the meat and this was the problem. All subsequent curing methods from time immemorial, which is the subject of this work, were done to reduce this time. With the 20:20 hindsight we have peering back over aeons of time, we realise that what they were looking for was other ways to speed up the production of Nitric Oxide which is the curing molecule with its reddening effect on the meat and its broad spectrum antimicrobial activity.

The earliest progression from salt-only curing was the addition of nitrate directly through saltpetre and the oxidation of ammonium. This article sets out this progression. Following World War 1, nitrite was added directly and right from the start this was controversial. The motivation for the change from nitrate to nitrite was the availability of nitrate in a war situation and secondly, the speed of curing with nitrite curing being much faster than nitrate curing. Since that time, and especially from the 60s and 70s, the curing industry tried to find a system that does not rely on nitrate or nitrite. I believe this was done based on an inadequate understanding of the role of nitrate and nitrite in human health but it’s a discussion for another time. (The Truth About Meat Curing: What the popular media do NOT want you to know!)

When the industry found this to be impossible (curing without nitrate or nitrite), a trend began where some denied its inclusion in meat or at least tried to hide it. They did this by using an ancient method of curing where plants and fruits are used, naturally high in nitrate and nitrite but label declaration legislation does not necessitate you to declare all the chemical species naturally found in the plant matter. So, it is still nitrate and nitrite added to the meat which produces the nitric oxide which cures the meat, but using this strategy, producers did not have to include nitrate or nitrite on their labels.

Using this method of curing results in a healthier product due to the inclusion of minerals, vitamins, antioxidants and other beneficial plant constituents but to claim no-nitrite/ nitrate curing is false. A contemporary example of this may be the recent launch of Woolworths in South Africa.

Woolworths in South Africa launched a range of bacon recently which they claim to be cured without nitrite. They state on their packaging that their bacon is cured “using a combination of fruit and spice extracts without compromising on flavour, texture or colour, and it contains no nitrites.” The question is what “contains no nitrites?” Is it the bacon that contains no nitrites or the curing brine?

Maybe they added these indirectly through plant matter which, in the end, is exactly the same thing as adding it directly with a major difference being that adding it through plant matter makes the process uncontrolled – meaning they can’t control how much they add as opposed to the method of adding nitrate and nitrite directly which enables you to reduce the amount of ingoing nitrate and nitrite to the smallest possible ratio which is the “safest” way of doing it if you believe that nitrates and nitrites are bad for your health (an assumption that I do not subscribe to, see The Truth About Meat Curing: What the popular media do NOT want you to know!)  Whatever the consequence of adding it through plant matter, claiming “no nitrites” will be a blatantly false statement and I don’t believe this is what they are doing for one moment.

Of course, the “contain no nitrites” may mean that they took care to remove all residual nitrites from the bacon after it was cured. Residual nitrites are what is left in the bacon after curing. I will argue that nitrates and nitrates is not a big deal (The Truth About Meat Curing: What the popular media do NOT want you to know!) but I understand many consumers still have a negative perception of nitrites and if the products are not formulated right, it poses a problem. Residual nitrites can be reduced dramatically by employing a range of processing techniques and through bacteria. Staphylococcus xylosus and Staphylococcus carnosus have, for example, been shown to be also able to reduce the residual amounts of nitrates and nitrites (Neubauer and Götz, 1996; Gøtterup et al., 2007; Mah and Hwang, 2009; Bosse et al., 2016). Woolworths is a quality-driven company their statement, “contain no nitrites” means that they used nitrates and nitrites but removed any traces of it before its made available for sale, I applaud them for their work! There is a small technical matter related to the chemical generation of nitrate from nitric oxide in a meat system and the fact that nitrite will soon be generated through bacterial action which calls into question if one can call any cured meat system 100% free from nitrites, but that is a question for another forum and it is possible with the right approach.

All this is an example of how the industry is grappling with the fact that nitrates/ nitrites are used. Before any of this became an issue in the world, there was curing with salt only. It would seem to me that at the heart of the entire move away from salt-only-curing was the fact that we fundamentally missed the role of microorganisms with the ability to react with protein and to create nitric oxide which then cures the meat. Well, we “missed” it because it was so hard to see nor did we have the technology to identify and isolate certain bacteria with this ability, nor did we understand what bacteria need to be effective by way of nutrition.

We had glimpses of this from the world of salt-only curing! The mechanisms underpinning salt-only curing are only emerging now as a powerful method to cure meat without the use of nitrate or nitrite, directly or indirectly. Let me say it like this. Now that we are working out the mechanism of salt-only curing, we discover ways to do it as quickly as is done with nitrite curing. Despite many years of intense research into meat curing, it is remarkable that we are only now starting to understand how the oldest form of curing works.

Proteins and lipids or fats in meat tissues are degraded mainly by enzymes which are also present in the meat during the ripening of the hams/ bacon but the breakdown of proteins and fat cells is also achieved through bacteria (Flores and Toldrá, 2011) and they play a direct role in curing in salt-only systems. Morita et al. found that Nitric Oxide formed in salt-only curing systems is achieved from L-arginine due to nitric oxide synthase (NOS) in either Staphylococci or Lactobacilli. (Morita et al., 1998 and quoted by Gasasira, et al, 2013) Another study on the production of cured meat colour in nitrite-free sausages by Lactobacillus fermentum showed that nitrosylmyoglobin (a form of the meat protein, myoglobin, formed during curing) could be generated when the bacteria, Lactobacillus fermentum AS1.1880 was inoculated into the meat batter, and the formation of a characteristic pink colour with an intensity comparable to that in nitrite-cured sausage can be achieved using 10⁸ CFU/g of the culture. In other words, bacteria, in a salt-only curing system can directly achieve what nitrite curing would later accomplish.

Despite the fact that even in the 1950s salt-only-curing was the biggest single way that bacon was produced on farms in the USA, I am going to look at two important salt-only-cured hams that have been the subject of research which elucidated the mechanisms underpinning salt-only-curing and to illustrate that the key, understanding the mechanism behind salt-only-curing, is bacteria. Microorganisms drive the process!

Parma ham is traditionally produced using only sodium chloride without the addition of nitrate or nitrite and develops a deep red colour, which is stable also on exposure to air. It has been shown that bacteria are responsible for the creation of nitric oxide without nitrate or nitrite which then cures the hams. Fascinatingly, despite the fact that we know that bacteria are responsible for the creation of nitric oxide which leads to nitrosylated heme pigments, the identity of the pigment of Parma ham has not been established. In one study, the stability of the pigment isolated from two different types of dry-cured ham (made with or without nitrite) was compared to that of the NO derivative of myoglobin formed by bacterial activity. Heme pigment from Parma ham made without nitrite was more stable against oxidation than the pigment from dry-cured ham with added nitrite.” (Møller and Skibsted, 2001) This is a most fascinating discovery! Further, heme pigments extracted from Parma ham and a bacterial (Staphylococcus xylosus) formed NO-heme derivative and have similar spectral characteristics (UV/ vis spectra and ESR).”  (Møller and Skibsted, 2001)

In China, Nuodeng ham is a dry-cured ham, traditionally made by Bai ethnic people in the Nuodeng village, Dali, Yunnan Province. As part of the production process, they use mineral-rich local salt reserves, and distilled corn liquor and rely on the favourable climate. From these hams, Kocuria rhizophila was isolated (Shi, 2021) and is probably responsible for the formation of the cured colour.

I can give many more examples. Dry-cured, long-cured or salt-only systems are in part enabled by bacterial action where the meat itself is fermented, nitric oxide is generated and the meat is cured. I return to this subject in the very last section of this article under the heading Bacterial Fermentation Curing. Woolworths in South Africa may very well rely on this mechanism of curing their bacon which is the only system where they can make the claim that nitrite is not present. If one would test their cure or their bacon at any time immediately following curing and in the time that it spends on the retail shelf or in the consumer’s refrigerator and nitrite is found, it will make their claim that no nitrites are present, false.

Besides the option of using plant matter that contains nitrate or nitrite, they could of course create the cured colour with proteins outside the meat environment and infuse these into the meat, which I doubt is what they are doing. They could use nitrite to cure the meat directly or indirectly and add bacteria that eliminates all nitrites post curing which is possible, but I would think improbable. The last option is that they could use nitrites at a level below 10 parts per million which will still cure the meat but is undetected in certain methods of testing for nitrites. The challenge will be that at those low levels the nitrite offers little protection against dangerous microorganisms but I notice that they add rosemary extract which could bolster this protecting mechanism. If this is what they are doing, it would unfortunately again make their claim of “contain no nitrites“, false. If, and I am by no means suggesting they are doing this, a clue would be if they are very sensitive to environmental exposure to nitrites during production as this could push the levels of nitrite in the bacon into the levels which are “detectable”.

The last option would be “underhanded” and with a company like Woolworths, there is no chance that they employ such a strategy. Friends of mine work in their meat department both in the compliance as well as operational departments and they would never be a party to anything not completely truthful. Well done to Woolworths then on your product which can only be using some form of fermentation.

Bacterial fermentation of meat is probably the closest one will ever get to a no-nitrite system which is a spectacular return to salt-only curing. Working out how to do it is, as the saying goes, the million-dollar question and if Woolworths found the way, I salute you! As far as our consideration of curing systems goes, our first consideration of curing, namely salt-only, will also be our final consideration under Bacterial Fermentation Curing. In between these two is the most fascinating story never told!

Origins of Nitrate/ Nitrite curing

This study of salt also brings me back to my work on nitrite/ nitrate curing which has been a major focus for me over many years. While people living in desert areas would have discovered that certain salts have the ability to change the colour of meat from brown, back to pinkish/ reddish, along with increased preservation power and a slightly distinct taste, coastal dwellers would have observed the same. They would have noticed that sea salt or bay salt have the same ability.

Dr Francois Mellett, the renowned South African food scientist, sent me the following very interesting theory about the earliest discovery of the curing process in private communication between us on the matter. He wrote, “I have a theory that curing started even earlier by early seafarers: when a protein is placed in seawater, the surface amino acids are de-aminated to form nitrite for a period of 4 to 6 weeks. Nitrite is then converted to nitrate over the next 4 weeks. Finally, ammonia and ammoniac are formed from nitrate. It is possible that they preserved meat in seawater barrels and that the whole process of curing was discovered accidentally.”

I favour the following explanation also related to meat being stored in water. Since proteins contain nitrogen when the meat is placed in seawater, the surface proteins are proteolised and deaminated to ammonia. The process is called ammonification and happens quickly in water. Ammonia or ammonium is oxidised to nitrite in a process that is referred to as nitration by ammonia oxidising bacteria (AOB). Nitrite is oxidised by nitrite oxidising bacteria (NOB) in the second step of nitrification. (Domingos, 2011)

I suspect that people discovered this even long before barrels were invented. The use of seawater for meat storage and further preparation was so widespread that it would have been impossible not to have noticed meat curing taking place. If it is generally true that the earliest humans first settled around coastal locations before migrating inland, and if the seaside communities first noticed curing, it would push the discovery of curing many thousands of years earlier than we ever imagined, to a time when modern humans started spreading around the globe. When did it develop into an art or a trade is another question altogether, but I think we can safely push this back to the earliest cognitive and cultured humans whom we would have recognized as thinking “like us” if we could travel back in time and meet them.

We know that dry-curing of pork takes around 5 to 6 weeks under the right conditions and if the meat is not cut too thick. It must be cool enough that the meat doesn’t spoil before it is cured.  Even though I now suspect that curing was first noticed by communities living by the sea as I just explained, I suspect that curing salts in deserts were discovered since natural salts always appear as a mix of various salts and under certain conditions, these salt deposits contain small amounts of nitrate salts and ammonium chloride. This would have aided its development into an art by the much larger availability of nitrate and related salts.

I deal with these salts below under separate headings, but the most important two curing salts that appear to us from antiquity are saltpetre (sodium nitrate) and sal ammoniac (ammonium chloride).  Both salts were well known in Mesopotamia and references to them appear alongside references to salt curing of fish mentioned earlier and both salts were used in meat curing.

The ancients developed basic techniques of separating out the different salts. In particular, sal ammoniac was by far the more important salt of the bronze age (2000 BCE). It was produced in Egypt and mined in Asia where it occurs naturally. There are features of sal ammoniac that favour it as a salt for people who had a motivation to exploit new lands due to population pressure and climate changes or just curiosity. When the horse was domesticated around 5000 BCE, a food source was needed to sustain humans on long expeditions and I believe sal ammoniac fits the requirement perfectly.

Both salts cure the meat in a week which obviously had huge advantages over salt-only curing. This, I speculate, was the first incentive to change to a dedicated curing salt. Secondly, sal ammoniac, as far as I can find, was globally traded from much earlier on than saltpetre. Ancient Macedonian records indicate that even 2000BCE saltpetre was preferred in food over sal ammoniac on account of the better taste of saltpetre.

There is a modern-era example of a curing technique that was good for a time and was then replaced with more agreeable methods as soon as supply lines were established. This technique, I believe, actually existed from very early after the horse was domesticated and was re-introduced by various cultures at various times. One such culture was the Boers, who left the Cape Colony and moved into the interior of South Africa. The technique they used to cure their meat disappeared as soon as conventional supply lines were established.

The technique is curing meat by hanging it over the neck of the horse or placing it under your saddle so that the sweat of the horse cure the meat. (For a discussion on this, see my article, Saltpeter, Horse Sweat and Biltong) My point is that this is a good example of a curing technique that was used for a time only and then disappeared, only to re-appear when conditions required it. Such was the case, I suspect when sal ammoniac was used for a time in curing until the requirement subsided, salt curing became popular again, and much later, economic factors re-introduced an improved curing salt which by this time was saltpetre. The inclusion of saltpetre into curing salt mixes goes hand in hand with its increased availability.

Thomas Thomson, commenting on the the Muslim alchemist who lived in the 700s and 800s says that Geber (Abū Mūsā Jābir ibn Ḥayyān) was as far as he could tell, the earliest to mention saltpeter. In contrast to this, in that time, sal ammoniac “seems to have been quite common in his time.” (Thomson, 1830) Beckmann (1846) suggests that Europe became familiar with sal-amoniac in the 12th century and following.

German and Austrian cookbooks pre-1600s reveal that vegetable dyes were used to bolster colour at this time and speak of curing with salt only. It is well known that the Germans, and Austrians were familiar with nitrate curing and, I will argue, they would have been acquainted with sal ammoniac as a curing salt also, but for whatever reason, these fell out of common practice. When the requirements disappeared for nitrate and sal ammoniac curing in the ancient world, the nations of Europe and China reverted to salt curing.

The many references to salt curing are therefore not surprising in the context of a mature and stable society. A record exists from Cato the Elder who described in 160 BCE how a ham should be cured.  In his Latin work, De Agricultura (On Farming), this Roman statesman and farmer, gives an ancient recipe for curing pork with salt.

“After buying legs of pork, cut off the `feet. One-half peck ground Roman salt per ham. Spread the salt in the base of a vat or jar, then place a ham with the skin facing downwards. Cover completely with salt. After standing in salt for five days, take all hams out with the salt. Put those that were above below, and so rearrange and replace. After a total of 12 days take out the hams, clean off the salt and hang in the fresh air for two days. On the third day take down, rub all over with oil, hang in smoke for two days…take down, rub all over with a mixture of oil and vinegar and hang in the meat store. Neither moths nor worms will attack it.” (economist.com)

Cato may have imitated a process whereby hams are smoked over juniper and beech wood. The process was probably imported by the Roman gourmets from Germania. (economist.com) It is possible that the process of curing itself was brought to Rome by the military stationed in Germany.

Salt curing remains an important technique for high-end hams and certain bacon. Like nitrite curing, it yields a particular cured colour, but one that is a deeper purple than pink.  For the mechanism behind this, refer to a section in my article on the mechanisms of nitrite curing, Bacterial/ Enzymatic Creation of Cured Colour. This is entirely restricted to long-term curing which was the norm at a certain time.

Sal Ammoniac

In 2017 I did an article where I speculated that nitrate curing originated from either the Turpan area in western China or from the Atacama desert in Chile and Peru. In this article, I suggest that nitrate curing of meat is thousands of years old. (Salt – 7000 years of meat-curing) I was working on the assumption that nitrate salts are the only salts that will yield nitrite and nitric oxide, required for meat curing. Between the Atacama desert and Turpan in Western China, Turpan is by far the best candidate for the birthplace of meat curing as it is practiced around the world. I recently review further evidence from this area in an article, Nitrate Salts Epic Journey and And then the mummies spoke!

In the course of researching the article, I discovered that sal ammoniac was far more vigorously traded than saltpetre in the early Christian era and possibly for thousands of years before that. Fascinatingly enough, I realised that ammonium chloride will, like nitrates, undergo bacterial transformation into nitrites which will then in the meat matrix yield nitric oxide which will cure the meat. I further discovered that it is an excellent meat preservative, even better than nitrates. Turpan is also probably the only place on earth where sal ammoniac and nitrate salts in the form of sodium nitrate occur in massive quantities side by side.

Chinese authors of antiquity are unanimous that sal ammoniac came into China from Turpan, Tibet, and Samarkand, and through Samarkand, it was traded into the Mediterranian along the silk road. There are similar records that it was traded from Turpan along the silk road through the city of Samarkand which had strong trading ties with the Mediterranean. It all makes for an appealing case for sal ammoniac as the actual curing salt from antiquity that was used in meat curing when the practice spread around the world. There is even a tantalizing link between Turfan and the ancient city of Salzburg in that a very particular stitch was found in jerseys on mummies in Turfan and in salt mines in Salzburg. This leads me to speculate that the trade of sal ammoniac was done into the heart of Western Europe, into what became known as Austria. This leads me to believe that the actual technological progressions may have come from Austria. Whether it was Salzburg or Turfan is not clear. More work remains to be done to gain greater insight.

We are not familiar with this salt in the context of meat curing and it will be in order for me to dwell on the topic a bit. I reviewed modern references dating back to the 1700s, 1800s, and 1900s where it continued to be used in meat preservation in Nitrate Salts Epic Journey. Several minerals exist composed of ammonium (NH₄). Ammonium is formed by the protonation of ammonia (NH₃). Sal ammoniac is the most well-known and was named by the ancient Romans.  They collected this salt which was found around the temple of Jupiter Ammon in Egypt and called it salt (sal) of Ammon (ammonocius). The name ammonia was subsequently derived from it. It forms in volcanic vents and after volcanic eruptions before it has rained which dissolves it. It is highly soluble. It is unique in that the crystals are formed directly from the gas fumes and bypass the liquid phase, a process known as sublimation.

Ammonium readily combines with an acid thus forming a salt such as hydrochloric acid to form ammonium chloride (sal-ammoniac) and with nitric acid to form ammonium nitrate. Recent studies have shown that volcanos release a “previously unconsidered flux of nitric acid vapour to the atmosphere. (Mather, T. A., et al, 2004) It is a fascinating and insightful fact that the Turfan area, both the basin and the mountains are replete with different salts containing nitrogen (nitrate salts and ammonium) any one of which could be used effectively in meat curing.

Sal ammonia was mined from openings in the sides of volcanic mountains where steam from underground lava flows created the ammonium chloride crystals. These were traded across Asia, Europe and India. Massive sodium nitrate deposits occur in the Tarim Basin, the second-lowest point on earth. I then speculate that traders used some of these deposits to forge ammonium chloride since the ammonium chloride crystals did not survive in crystal form on long voyages due to their affinity for water which breaks the crystal structure down. Once this happened, the sodium nitrate and the ammonium chloride look similar in appearance. Due to the fact that it is known that almost all the sal ammonia mined in Samarkand was exported, I deduce that demand outstripped supply and this provided the incentive for such forgery. I find support for the likelihood of such a forgery, not just in the limited supply of sal ammoniac compared to nitrate salts, but also in the fact that mining then sal ammoniac was a seasonal affair and extremely dangerous and a difficult undertaking.

It seems likely that sal ammonia was the forerunner of saltpetre as the curing agent of choice. It is composed of two ions, ammonium and chloride. The ammonium would be oxidized by ammonia-oxidizing bacteria (AOB) into nitrites and the well-known reaction sequence would result. (Reaction Sequence)

Not only would it result in the reddish-pinkish cured colour, but it was an excellent preservative. In my personal experience, it is a better preservative than salt and nitrites alone, but more work is needed to confirm this. There is, however some evidence of this fact from history. An 1833 book on French cooking, The Cook and Housewife’s Manual by Christian Isobel Johnstone states that “crude sal ammonia is an article of which a little goes far in preserving meat, without making it salt.” (Johnstone, C. I.; 1833: 412) It is, of course, the sodium which tastes salty in sodium chloride and ammonium chloride will have an astringent, salty taste. I know exactly what ammonium chloride tastes like since it was added to my favourite Dutch candy “Zoute Drop” with liquorice. I believe it was none other than my old friend, Jan Bernardo, who first gave me Zoute Drop. As a boy, I used to ride my bicycle once a month to the only Greek Caffe in Vanderbijlpark, which sold it for my monthly fix. My favourite was the double-strength version called “Dubbel Zoute Drop.”

Subsequent to these discoveries, I did two small tests with sal ammoniac. Refer to The Sal Ammoniac Project.  Here I show that sal ammoniac stands up to its reputation as an excellent preservative and definitely cures meat in two weeks at a 5 deg C temperature.

Salt with a little bit of saltpetre

Saltpetre is the curing salt that most of us are familiar with that preceded sodium nitrite as curing agent. By far the largest natural known deposits of saltpetre to the Western world of the 1600s were found in India and the East Indian Companies of England and Holland plaid pivotal roles in facilitating its acquisition and transport. The massive nitrate fields of the Atacama desert and those of the Tarim Bason were still largely unknown. In 1300, 1400 and 1500 saltpetre had, however, become the interest of all governments in India and there was a huge development in local saltpetre production.

In Europe, references to natron emerged from the middle of the 1500s and were used by scholars who traveled to the East where they encountered both the substance and the terminology. Natron was originally the word that referred to saltpetre. Later, the word natron was changed and nitron was used.

At first, the saltpetre fields of Bihar were the focus of the Dutch East Indian Company (VOC) and the British East Indian Company (EIC). The VOC dominated the saltpetre trade at this point. In the 1750s, the English East Indian Company (EIC) was militarised. Events soon took place that allowed for the monopolization of the saltpetre trade. In 1757 the British took over Subah of Bengal; a VOC expeditionary force was defeated in 1759 at Bedara; and finally, the British defeated the Mughals at Buxar in 1764 which secured the EIC’s control over Bihar. The British seized Bengal and took possession of 70% of the world’s saltpetre production during the latter part of the 1700s. (Frey, J. W.; 2009: 508 – 509)

The application of nitrate in meat curing in Europe rose as it became more generally available. Later, massive deposits of sodium nitrate were discovered in the Atacama Desert of Chile and Peru and became known as Chilean Saltpeter. Curing with this was, as I have said before, only a re-introduction of technology that existed since well before 2000 BCE.

The pivotal area where I believe saltpetre technology spread from across Asia, India and into Europe, is the Turpan-Hami Basin in the Taklimakan Desert in China. Here, nitrate deposits are so substantial, that an estimated 2.5 billion tons exist, comparable in scale to the Atacama Desert super-scale nitrate deposit in Chile. (Qin, Y., et al; 2012)  (The Tarim Mummies of China) Its strategic location on the silk road, the evidence of advanced medical uses of nitrates from very early on and the ethnic link with Europe of people who lived here, all support this hypothesis.

Large saltpetre industries sprang to the South in India and to the South East in western China. In India, a large saltpetre industry developed in the north on the border with Nepal – in the state of Bihar, in particular, around the capital, Patna; in West Bengal and in Uttar Pradesh (Salkind, N. J. (edit), 2006: 519). Here, it was probably the monsoon rains that drench arid ground and as the soil dries during the dry season, capillary action pulls nitrate salts from deep underground to the surface where they are collected and refined. It is speculated that the source of the nitrates may be human and animal urine. Technology to refine saltpetre probably only arrived on Indian soil in the 1300s. Both the technology to process it and a robust trade in sal ammoniac in China, particularly in western China, predate the development of the Indian industry. It is therefore unlikely that India was the birthplace of curing. Saltpetre technology probably came from China, however, India, through the Dutch East Indian Company and later, the English East Indian Company became the major source of saltpetre in the west.

To the South East, in China, the largest production base of saltpetre was discovered dating back to a thousand years ago. Here, a network of caves was discovered in 2003 in the Laojun Mountains in Sichuan Province – possibly the largest production base of saltpetre in China from 1000 years ago. Meat curing interestingly enough is also centred around the western and southern parts of China. Probably a similar development to the Indian progression.

In China, in particular, a very strong tradition of meat curing developed after saltpetre was possibly first introduced to the Chinese well before 2000 BCE. Its use in meat curing only became popular in Europe between 1600 and 1750 and it became universally used in these regions towards the end of 1700. Its usage most certainly coincided with its availability and price. I have not compared price and availability in Europe with the findings on its use in meat curing which is based upon an examination of German and Austrian kook books by Lauder (1991), but I am confident that when I get to it one day, the facts will prove the same.

The Dutch and English arrived in India after 1600 with the first shipment of saltpetre from this region to Europe in 1618. Availability in Europe was, generally speaking, restricted to governments who, at this time, increasingly used it in warfare. (Frey, J. W.;  2009) This correlates well with the proposed time when it became generally available to the European population as the 1700s from Lauder. I believe that a strong case is emerging that the link between Western Europe and the desert regions of Western China was the place where nitrate curing developed into an art. The exact place, I believe, in Western China is the Tarim depression.

Heuzenroeder (2006) reports that recipes for early ham brines in Germany did not include saltpetre. Remember that the first shipment of saltpetre from India reached Europe only in 1618. Heuzenroeder (2006) reports that recipes for early ham brines in Germany did not include saltpetre. Remember that the first shipment of saltpetre from India reached Europe only in 1618. In Chapter 05.00: Evaluation of Dry Curing with Saltpeter (with and without sugar) under Vegetable Dies we look at the use of plant matter to colour meat during the 1600s. In all likelihood, this had more to do with the nitrates inherent in these plants than the actual colour it provided.

Making ham and bacon without adding saltpetre continues to be a tradition in certain Barossa families and I would suspect them to be using techniques that “unlocks” the formation of nitrite which converts to nitric oxide or the creation of nitric oxide directly. “The Hentschke family continued to use a wooden pickle barrel and immerse their bacon and ham in pure salt brine for a week to a fortnight as late as 1939.” The reason for the effectiveness of this method has been discussed under “Origins of Nitrate/ Nitrite curing?” above. Two weeks will be enough time for curing to take place.

Heuzenroeder (2006) says that early in the 1900s many families adopted another method. “Recipes started to appear in woman’s private notebooks for boiling a pickle brine of water, salt, saltpetre, sugar and pepper in a clean kerosene tin, into which the meat was immersed and then kept cool for about three weeks. The Australasian Butchers’ Manual of 1912 advocated this more efficient method also, saying that the old dry-salting process was ‘simply a waste of time.’ The lateral use of the kerosene tin, a common farm commodity, made possible a new technique which must have altered the texture and flavours of the hams considering the difference in saltpetre and salt concentrations between the boiled and the naturally induced brines and the difference in the length of time of immersion.” (Heuzenroeder, 2006) When heated above 300^oC, the saltpetre decomposes into nitrite and oxygen. It is then the nitrite that penetrates the meat and is further reduced to nitric oxide which cures the meat.

Placing the meat in the water while it is still warm will speed up the process of diffusing the brine through the meat. It would not have been done if the water was warmer than around 50oC because it would have resulted in the denaturing of the proteins. Boiling water would definitely not have worked. Adding sugar and salt raises the boiling temperature of the water. Whether enough would be added to make a temperature of 300^oC possible is debatable. Failing this strategy, the well-known bacterial reduction of nitrate to nitrite would have followed.

Dry curing of meat changed from salt only to a mixture of salt and saltpetre, liberally rubbed over the meat.  As it migrates into the meat, water and blood are extracted and drained off.  The meat is usually laid skin down and all exposed meat is plastered with a mixture of salt and saltpetre.  Pork bellies would cure in approximately 14 days. (3) (Hui, Y. H., 2012: 540)

Salt, Saltpeter, and Sugar

The addition of sugar which favours the reduction of nitrate to the active agent nitrite became common practice during the 19th century.” (Lauer K. 1991.) At first, it was added to reduce the saltiness of the meat and make it generally more palatable. Curers soon discovered that when sugar is added, the meat cures faster and the colour development is better.

Science later revealed that the sugars contribute to “maintaining acid and reducing conditions favourable” for the formation of nitric oxide.” (Kraybill, H. R..  2009)  “Under certain conditions reducing sugars are more effective than nonreducing sugars, but this difference is not due to the reducing sugar itself. The exact mechanism of the action of the sugars is not known. It may be dependent upon their utilisation by microorganisms or the enzymatic systems of the meat tissues.” (Kraybill, H. R..  2009)

Ralph Hoagland, Senior Biochemist, Biochemie Division, Bureau of Animal Industry, United States Department of Agriculture, discovered that saltpetre’s functional value upon the colour of meat is its reduction to nitrites and the nitrites to nitric oxide, with the consequent production of NO-hemoglobin. He showed that the reactant is nitrous acid () or one of its metabolites such as nitric oxide ().

He wrote an important article in 1921, Substitutes for Sucrose in Cured Meats. Writing at this time, this formidable meat scientist is ideally placed to comment on the use of sugar in meat curing in the 1800s since the basis of its use would have been rooted in history.

He writes about the use of sugar in meat curing in the USA and says that it is used “extensively.” He reveals that according to government records, 15,924,009 pounds of sugar and 1,712,008 pounds of syrup, totaling 17,636,017 was used in curing meats in pickle in establishments that were inspected by the US Government, in 1917. If one would add the estimated use of sugar in dry cures in the same year, he placed the usage at an estimated total of 20,000,000 pounds. This estimate excludes the use of sugar in meat curing on farms. (Hoagland, 1921.)

Hoagland says that the functional value of sugar in meat curing at this time (and probably reaching back into the 1800s) was entirely related to product quality and not preservation. “Sugar-cured” hams and bacon were viewed as being of superior quality. He states that a very large portion of bacon and hams produced in the USA are cured with sugar or syrup added to the cure. The quantity of sugar used in the curing mix is so small that it does not contribute to meat preservation at all.  “Meat can be cured in entire safety without the use of sugar, and large quantities are so cured.”  (Hoagland, 1921.)

The contribution to quality that he speaks about is probably related to both colour and flavour development. The colour development would have been related to the formation of the cured colour of the meat (The Naming of Prague Salt) as well as the browning during frying.

The role of sugar in bacon curing of the 1800s when saltpetre was used was elucidated in 1882 by Gayon and Dupetit, studying and coining the term “denitrification” by bacteria. The process whereby nitrate is changed to nitrite is through the process of bacterial denitrification. They demonstrated the effect of heat and oxygen on this process and more importantly for our present discussion, “they also showed that individual organic compounds such as sugars, oils, and alcohols could supplant complex organic materials and serve as reductants for nitrate.”  (Payne, 1986)

Denitrifying bacteria are facultative anaerobes, that is, they will only use nitrate () if oxygen () is unavailable as the terminal electron acceptor in respiration.”  “The  is sequentially reduced to more reduced forms although not all bacteria form gas. ” “Many bacteria can only carry out the reduction of  to , and this process is referred to as dissimilatory nitrate reduction. There is also evidence emerging that certain bacteria can denitrify, even if   is present.  (Seviour, R. J., et al..  1999:  31)

(Seviour, R. J., et al..  1999:  31)

“The rate of denitrification is affected by several parameters including temperature, dissolved oxygen levels and the concentration and biodegradability of carbon sources available to these cells” (Seviour, R. J., et al..  1999:  223) Examples of such carbon sources are sugar, oxygen and plant oils.

In the 1800s when the use of saltpetre was at its pinnacle, the use of sugar with saltpetre had then a much more prominent role in that it energizes denitrification bacteria which results in an increased rate of nitrate reduction to nitrite and therefore would speed up curing with saltpetre and result in a better overall curing process. Today, with the widespread use of sodium nitrite in curing brines, certain denitrifying bacteria is one mechanism for NO formation which directly leads to better curing. The use of sugar or dextrose in bacon production in the modern era has more to do with the browning effect through the well-known Millard reaction to give fried bacon a nice dark caramel colour when fried.

Double Salting

In order to dry the meat quicker, a practice developed to salt it multiple times. During the first salting, meat juices are pulled from the meat. This was cleared away and a second “salting” was administered. Later on, several “saltings” were administered. Right here from the southernmost point of the African continent comes a great illustration of this from the early 1700s which then, easily extends back several hundred years.

Remember that the settlement which became Cape Town was in the first place set up as a refreshment station for the Dutch East Indian ships that rounded the African continent en route to India from Amsterdam. It became a stop-over for any friendly ship and Cape Town soon got the name of Tavern of the Sea. Here the summers are extremely hot from December to March or mid-April. Winter starts when the first Arctic cold fronts arrive in April and lasts till at least September. From September to December, it’s technically summer, but it’s often very cold and rainy with intermitted very hot spells. This means that April to August would be the only four months to properly cure meat which was very important for the Cape economy as it would be sold to passing ships. The pressure would have been relentless to find ways to cure meat in the other months also. This is then the background to the account of multiple saltings.

Upham reports on the following course of events from 1709. A detailed treatment of the reference can be seen at Saltpeter, Horse Sweat and Biltong. What was happening in the sweltering heat of March in Cape Town was that meat that was salted for sale to ships was off. A certain Michiel Ley then suggested that the meat should be salted in a two-step process. In other words, salt it and let it lay for a couple of days, giving time for blood and meat juices to be drawn out. Then, give it a second salting. Lay originally came to the Cape as a soldier employed by the Dutch East Indian Company but he changed his occupation to that of a master butcher. Certainly, this was his trade which he received in Europe.

An extract from 28 March 1709 from a Broad Council Meeting at the Cape of Good Hope gives us the rest of the story. It is clear from the entry that they were under pressure to supply due to both supply and increased demand. They noted, “Not one hardly offered himself for the supply of dried or smoked meat. Only 2,500 or 3,000 Ibs. were offered – a quantity very little among so many vessels. The necessity of supplying the ships properly is re-iterated.” The reason for the short supply was the prices offered by the Company which were too low and consequently the farmers were reluctant to sell.

The small quantity of meat that they received was itself unsuited for sale. They minuted that the “Governor and flag officers inspect some meat salted 8 days ago by the contractor Husing. The lean parts were found good, but the thick parts already spoiling“.

Michiel Ley came up with a plan that was accepted. “Decided that the treat should first lie some days in the brine to draw out the blood, and after that placed in new salt. That was not the idea of Husing but of his fellow contract or Michiel Ley. The former believed that the meat should be left in its first salt and not pickled beforehand; And was prepared to guarantee supply remaining good.” This dispute clearly shows that double salting was by no means an accepted technique in the 1600s and early 1700s.

The decision was made. “Decided, however, to adopt the plan of double salting, recommended by Ley; Husing ordered to supply in that manner; “Meervliet” having brought sufficient casks for the purpose. Ley to supply his share according to his plan. Company to supply the pepper.” The meat which was previously salted by Husing was also given over to Ley. “Decided to take over for the Company, the meat already salted by Husing. The good portions to be distributed among the crews, & the tainted ones among the slaves …”

So it happened that Lay was contracted to supply all the meat required by the Company together with Willem Basson, Jan Oberholster, and Anthony Abrahamsz. The issue of the supply of meat was major and shaped the immediate political landscape of the colony. Remember that we said that the prices offered by the Company for meat were too low and the farmers refused to sell. South Africans are well familiar with the fact that Van der Stell was recalled and that Adam Tas was involved in the saga. Adam Tas was one of these farmers and he took it upon himself to collect signatures for a petition against the governor at the Cape. Governor Van der Stel was eventually recalled to Holland. Van der Stel’s reply to the petition against him was a document drafted by him in his defence and signed by among others Ley and Oberholster. The four partners requested that their meat contract be cancelled which was granted and it was taken over by Claas Henderiksz Diepenaar. Adam Tas was locked up in the Castle’s notorious dungeon and finally, Van der Stel was recalled to Holland in 1708. The meat contract was the issue at the heart of Van der Stel’s recall.  (Linder) Ley acted as one of Van der Stel’s representatives to finalize the sale of his assets. (Stamouers)

Notice the black pepper which was added. The reason for this was probably to keep flies and other insects away.

Brine-soaking (brine cure – no pumping)

Brine-soaking followed dry-salt-curing. Note that dry or wet curing is defined by what the meat is left in to cure and not what is applied to the meat. Wet brine curing is still relatively slow and meat pieces are placed in a mixture of salt, saltpetre, and water. It is important to take temperature into account since spoilage may occur before the brine had a chance to penetrate the meat. (Hui, Y. H.,  2012: 540) Here the temperature is very important and is the reason why curing was only done in the winter months.

An 1830 description of a “wet cure” survived where a farmer describes the dry cure method as “tedious.” He credits Europe as the birthplace of the wet-cure method. One of the benefits of this simple system is that it can be used for mutton and beef also. The downside is that it is more expensive than dry-cure, but the wet cure could be re-used and taking everything into account, would work out cheaper in the long run than dry-cure. (The Complete Grazier, 1830:  304) It seems then that wet-curing was invented in the late 1700s or early 1800s.

This re-using of the brine would turn out to become the cornerstone of the industrial revolution for bacon curing and the country credited for this development is Ireland. Before we get to that, we have to first look at barrel pork.

Barrel pork

Barrel pork was an easy way to cure pork that involved liquid brine. It had the benefit that it could be put in barrels, loaded onto a wagon or a ship for transport and cure in transit. It could also be stored in the cure which would render it safe from flies and other insects. References to it show that it was practised already by the second half of the 1700s and well into the 1800s.

In the 1800s, this was the main way that the packing plants in the USA exported pork to England as bacon. There are many accounts in newspapers of the time where advice is given to the bacon producers on how to make sure that the meat arrives in England unspoiled. One of the main points was the importance of using good, new wood for the barrels.

A 1776 description is given on how barrel pork was produced. “After the meat has cooled < probably after the hair was removed >, it is cut into 5 lb. pieces which are then rubbed well with fine salt. The pieces are then placed between boards a weight brought to bear upon the upper board so as to squeeze out the blood. Afterward, the pieces are shaken to remove the surplus salt, [and] packed rather tightly in a barrel, which when full is closed. A hole is then drilled into the upper end and brine is allowed to fill the barrel at the top, the brine being made of 4 lb. of salt (1.8kg or 10%), 2 lb. of brown sugar (0.9kg or 5%), and 4 gallons of water (15L or 84%) with a touch of saltpetre. When no more brine can enter, the hole is closed. The method of preserving meat not only assures that it keeps longer but also gives it a rather good taste.” (Holland, LZ, 2003: 9, 10)

Again, notice the brine make-up of salt, saltpetre, sugar mixed with water. The role of the sugar was to break the hard salt taste.

Barrel pork would remain an important curing method throughout the 1700s and would make a spectacular return almost 100 years later when pressure pumps were introduced to inject the brine into the meat through needles.  A plank would be run across the barrel opening. The meat is placed on the plank for injection with between one and three needles. The three needles are fed brine through a hand pump that pumps brine directly from the barrel.  The barrel is half-filled with brine. After the meat has been injected, it is pushed off the plank to fall into the brine, which acts as a cover brine.  It would remain in the cover brine for the prescribed time before it is removed and smoked.

The invention of Mild Cured Bacon by William Oake

Sometime before 1837, William Oake, a chemist from Ireland, invented Mild Cured Bacon. (William Oakes Mild-Cured Bacon and Mild-Cured Bacon and the Curers of Wiltshire) This was the first major development in curing technology following barrel curing. The essence of mild curing is the continued reuse of the old brine. Oake was investigating what was responsible for the preservation power in the salt/saltpetre mix. He correctly concluded that salt plays a very limited role in preservation and today we know that its main function in old dry curing systems was to reduce the moisture in the meat and thus lowering the water activity. He also found no great preserving power in saltpetre but he knew that “nature” provided somehow a preserving power to the meat. The final power behind the reuse of the old brine took the rest of the 1800s to work out and was probably done in Denmark or definately in Wiltshire. It was known at this time that the reuse of old brine had a large benefit and we know that this probably came to England from the German region of Westphalia. (William Oakes Mild-Cured Bacon) So, at this time, there was a practice in England to reuse brine twice. One would cure the meat with the liquid brine, boil it to “clean it”, and re-use it a second time. (For a full discussion on this, see William and William Horwood Oake)

After a careful and detailed investigation of the curing techniques used in Westphalia, I came to the realisation that this, the key feature of William Oake’s Mild Cures system was a progression of a system developed years earlier, not in Westphalia but in the Russia of Catherina the Great! She (or someone in Russia or even possibly in her court) happened upon the idea that since salt is a scarce and very expensive commodity, as was the case in Russia at that time, a way to re-use, not the brine but the salt would be to boil the brine down after it was used, add sugar, saltpetre and salt to it with fresh spring water. The brine was called the Empress of Russia’s Brine and for a comprehensive discussion on the link between this brine and Westphalia, see Westphalia Bacon and Ham & the Empress of Russia’s Brine: Pre-cursers to Mild Cured Bacon. The clue to the close connection between a knowledge of this brine, possibly through Westphalia and Northern Ireland where William Oake invented mild-cured bacon is discussed in great detail in Mild Cured Bacon.

William Oake, a trained chemist must have worked out that boiling the brine was not necessary which is the only substantive change he made to the method of Catherina the Great! Oake’s major contribution was to look at the full process and reorganise it in a way that makes sense in a factory environment. He industrialised bacon production. He also realise that the brine can be used many more times than only twice and boiling it was not necessary. His work made great bacon affordable and available to the general public. His system incorporated the following elements.

• Lightly salting the meat to draw out the blood on the concrete factory floor

• Tanking or brining (stacking and pickling) for 7 days which involved sprinkling the bottom of the tank where the meat would be cured with salt. Stack the flitches on the bottom. Lightly sprinkle saltpetre over it with sugar and salt. The next layer of flitches is stacked on top of the first but done crosswise. This is again sprinkled exactly as was done with the first and so it is repeated till the tank is full. A lid is now placed inside the tank with an upright on top and pickle is poured into the tank. The lid and upright serve the purpose of keeping the bacon sides submerged. The pickle is made as follows: To every 10lbs. of salt we add 8lbs. of dark-brown sugar; 1 lib. of spice, and 1/2lb. of sal-prunella.” Sal prunella a mixture of refined nitre and soda.  Nitre is refined saltpetre used in the manufacturing of explosives. Saltpetre plays a very important role as does the grade of saltpetre used. It is important to turn the meat over after forty-eight hours into another tank.  The meat that was on top is placed at the bottom of the next tank. Salt, sugar, and saltpetre are again used exactly as it was done during the first salting. Now the real trick comes in. The same pickle is used!”

• Maturing/ Resting and Drying for 21 days. After seven days the flitches are removed and stacked on the floor putting some salt between each layer. Be careful not to stack it higher than four sides deep, until it has been on the floor for some days when it should be turned over, and stacked higher each time until the fourth week from the day it went into the tanks; the bacon will then be cured.”

• Washing, drying, trimming and smoking. Place the bacon in tanks of cold water. Here it is soaked overnight. The next morning we wash them well with a brush. Whether smoking is done or not after tank curing the meat should be rinsed off and dried before ageing or maturation. The reason for this is that the meat pores should be closed leading to a hardening of the surface and a considerable reduction in the drying rate. The meat is trimmed and hung till it is properly dried. It is then smoked. 

Two aspects should be noted. One is the rigid stepwise process which addressed efficiency, speed and hygiene and the second is the re-use of the old brine. Oakes’ genius was combining existing curing steps in a new way and the quality of his brine. His lasting contribution is, however, without any doubt, the creation of the live brine system which became the cornerstone of tank curing.

His use of sal prunella was, however a setback. Its inclusion in brine systems was nothing novel by 1830 with reference to its inclusion dating back to the 1700s. I suspect that sal prunella was for the most part not manufactured exactly as the intention was by heating saltpetre to boiling point which would have resulted in the formation of nitrite. It was heated and sulphur was added which resulted in saltpetre and sulphate. I suspect that the sulphate had an antimicrobial effect on the microbes who was supposed to convert the nitrates to nitrite, resulting in this conversion not taking place. I know this from the fact that the bacon lasted longer than traditionally cured bacon and the bacon was pale. The characteristic pinkish/reddish colour did not develop. The sulphites provided good antimicrobial protection along with the hygienic system of Oake’s, but no meat curing as we would define it today. (Mild-Cured Bacon and the Curers of Wiltshire) Mild Cured bacon was sold till after World War 1. It took many years to get rid of sal prunella in the cure and revert back to saltpetre only. It is, however clear that William Oake pioneered the repeated reuse of the old brine. Some companies reused the brines for decades. (William Oakes Mild-Cured Bacon)

The system was next adopted by the Danes. The year was 1880. Denmark is a tiny nation. To remain competitive, they realised years earlier to learn as much as they can from other nations and peoples and adapt. Every industry in Denmark was constantly looking at where new discoveries were being made and how they can adopt and adapt them.

Denmark had large dairy farmers and a sizable pork industry developed from the by-products of dairy farming. It was very simple and profitable. Raise pigs on the byproducts from milk and sell them to England and Germany. Someone from the pork industry learned about the new mild cured bacon produced in Ireland. They tried many times to send people to learn the techniques, but the Irish were careful not to employ the young Danish men who were sent over for employment in the large bacon plants in Ireland. They needed an opening in the Irish market to learn their techniques. Such an opening was presented through industrial action by the Irish workers. The thing about Ireland is that the workers often go on strike and how they are treated by the companies they work for is often very harsh. Those on strike do not get paid and stand a large chance to be laid off.

In 1880 there was a strike among butchers in the Irish town of Waterford. Some shrewd members of the Danish pork processing guild happened to be in Ireland at that time, in Waterford, and at the promise of lucrative employment in Denmark managed to persuade a number of the striking men to return with them to Denmark. In Denmark, they quickly arranged for them to train the Danish butchers. Mild Cured Bacon became the new Danish bacon.

Sweet Cured Bacon by C & T Harris (Dry-salt-curing in combination with injection)

In Calne, a small settlement in Wiltshire, England, the firm C & T Harris was becoming the world leader in producing exceptional mass-produced bacon. For a complete discussion, please read Sweet Cured Harris Bacon!

Their invention was very similar to the general method of William Oake’s Mild Cured Bacon with the notable exception of the re-use of the old brine. Very importantly, they hot-smoked their bacon after curing. Even more important was the fact that this invention in the 1840s used stitch pumping. Stitch pumping itself was invented around this time and it allowed for much quicker curing of the meat which together with hot smoking cut the curing time down and was a major improvement on the taste. It was not a hard salted taste, but a mild cure taste, and from there the name.

It seems that the basic distinguishing between dry and wet curing is not based on whether injection is applied or not, but the state of the salts that the meat is left in, even after it has been injected with a brine (mixture of salt and water). So, if it is packed in a dry mix, it is dry curing and if it is soaked in a brine, it is wet curing.

It was reported by some bacon curers that they used the dry-curing in conjunction with injection. In this case, the meat is injected with approximately 10% saturated brine solution, and the injected meat is then treated the usual way in the application of dry-salt-cure. There is a record showing that C & T Harris (Calne) used injection with their bacon from 1843. After it was dry-cured, the meat was smoked at a temperature of not higher than 38 deg C (100 deg F) in order to prevent nitrate burn which presents itself as green spots that appear on the meat. In the report, mention is also made that care should be taken if these products are stored to prevent damage from insects such as cheese skippers, mites, red-legged ham beetles, and larder beetles.  (Hui, Y. H.,  2012: 540) The result was sweet cured bacon!

The Injection of Meat

A short review of the invention of the practice of brine injection with needles is appropriate at this time. The practice started as a way to preserve cadavers. I remember an account I read of how Von Hombult and Guthrie went from house to house after a particularly heavy thunderstorm buying up the corpses of the deceased for their own medical studies. Before the age of refrigeration, preserving human remains to study the makeup of the human body would have received considerable attention and this was the first area where injection of meat was done for the purpose of preservation.

The link between meat preservation for sustenance and meat preservation for the study of anatomy is, as the link between meat injection and the medical establishment, one that is abundantly obvious if you just think about it for a minute, but not necessarily the first connection you make when you look at the different disciplines separately. The man who took front and centre stage in the development and progressed the practice of injecting preserving fluids into dead animal muscles for the purpose of preservation was Morgan.

Morgan’s Patent

It was a certain Mr Morgan, in England, who had a significant impact on popularising the technique of injecting a liquid brine into the meat in the first place. The motivation was to increase the rate of curing by getting the brine faster into the meat in order to reduce the time required for processing which became the basis of sweet-cured bacon.

In temperatures above 20 deg C, pork spoils in three days. By injecting a liquid brine into the meat at evenly spaced intervals, the brine diffuses more quickly through the meat. Morgan’s interest was the preservation of meat generally but included meat preservation for long sea voyages before the advent of refrigeration and not the curing of meat by farmers.

We encountered Mr Morgan in the work of Edward Smith, Foods, (1873). Smith wrote that “Mr Morgan devised an ingenious process by which the preserving material, composed of water, saltpetre, and salt, with or without flavouring matter, was distributed throughout the animal, and the tissue permeated and charged. His method was exemplified by him at a meeting of the Society of Arts, on April 13, 1854, when I [Edward Smit was] presided.” (Smith, 1873)

He describes how an animal is killed in the usual way, the chest opened and a metal pipe connected to the arterial system. Brine was pumped through gravity feed throughout the animal. Approximately 6 gallons were flushed through the system. Pressure was created to ensure that it was flushed into the small capillaries. Smith reported overall good results from the process with a few exceptions. He himself seemed unconvinced.

An article appeared in the Sydney Morning Herald that mentions Dr Morgan and his arterial injection method. An important observation from the article is the date of 1870. By this time, he is referred to as “Dr Morgan”, cluing us in about the timeline of Morgan’s life.

A second observation is a drawback of the system. The article states that “salting is the most common and best-known process of preservation (of meat), the principal modern novelty being Dr Morgan’s plan of injecting the saline solution into the arterial system – the principal objection to which has been that the meat so treated has been over-salted.” (Sydney Morning Herald, 1 March 1870, p 4) The brine mix that Mr Morgan suggested was 1 gallon of brine, ¼ to ½ lb. of sugar, ½ oz. of monophosphoric acid, a little spice and sauce to each cwt of meat. (Smith, E, 1873: 36)

Seventeen years after Smith met Morgan at the Society of Arts meeting, in 1871, Yeats reported that a certain “Professor Morgan in Dublin, proposed a method of preservation by injecting into the animal as soon as it is killed, a fluid preparation, consisting, to every hundredweight of meat, of one gallon of brine, half a pound of saltpeter, two pounds of sugar, half an ounce of monophosphoric acid, and a small quantity of spice.” (Yeats, J, 1871: 225)

The plan was widely tested at several factories in South America and by the Admiralty, who had reported that they had good results from the technique. (Yeats, J, 1871: 225, 226) It was in all likelihood the same Morgan that Smith reports on who, by 1871, became a professor in Dublin. Notice, as a matter of interest that he used the same basic brine mix of salt, water, saltpetre, sugar, monophosphoric acid and spices. This, together with the similarity in surname makes it quite certain that Mr Morgan, Dr Morgan and Prof. Morgan are the same person. In itself, this is an example of perseverance! In 1854 his arterial injection was met with scepticism whereas Yeats reports in 1871 that the Admiralty viewed his improved method.

Was this Morgan’s Invention?

The concept of arterial injection was not new. By the time Morgan demonstrated it to the Society of Arts, on April 13, 1854, it may have been as old as 150 years, used for embalming corpses for the purpose of medical studies. This invention is credited by some to the Dutch physician, Frederik Ruysch (1638 – 1730). He injected a preservative chemical solution, liquor balsamicum, into the blood vessels, but his technique remained largely unknown for some time. (Bremmer, E.; 2014)

British scientists who used arterial injection and from whom Morgan could have learned the system were the Hunter brothers William (1718–1783) and John (1728–1793) and their nephew, Matthew Baillie (1761–1823). The injection was into the femoral arteries. They all injected different oils, mainly oil of turpentine, to which they added Venice turpentine, oil of chamomile, and oil of lavender. Vermillion was used as a dye to create a more life-like skin colour, but would also have added preservation to the final solution. (Bremmer, E.; 2014)

There is a reference from 1837, on an essay delivered on the operation of poisonous agents upon the living body by Mr John Morgan (1797 – 1847), F.L.S Surgeon to Guy’s Hospital. (1837; Works on Medicine) The same publication contains an article by Dr Baillie, M.D. on the morbid anatomy of some of the most important parts of the human body. John Morgan was undoubtedly well familiar with arterial injection. Not only due to the fact that he was a contemporary of Baillie, but he was also a demonstrator of anatomy at the private school near Guy’s Hospital. (livesonline.rcseng.ac.uk/) The late 1830 article that is referenced means that it fits the timeline perfectly for a late 1830 or early 1840 technology transfer for the use of the same general technique of injecting preserving fluids into the meat of a pigs carcass which presumably became stitch pumping, a precursor for Morgans invention.

John Morgan is in all likelihood the father of Dr John Morgan (Circa 1863), who was professor of anatomy at the University of Dublin. A process of arterial injection is described that was used by Dr John Morgan from the University of Dublin. ” John Morgan, a professor of anatomy at the University of Dublin in Ireland, formally established two principles for producing the best embalming results: injection of the solution into the largest artery possible and use of pressure to push the solution through the blood vessels. He also was among the first to make use of a preinjection solution as well as a controlled drainage technique. Morgan’s method required that the body be opened so the heart was visible, then an 8-inch pipe was inserted into the left ventricle or aorta. The pipe was connected to yards of tubing ending in a fluid container hung above the corpse. The force of gravity acting on the liquid above the body would exert about 5 pounds of pressure, adequate to the purpose of permeating the body.” (Wohl, V.) This process described here is applied, not to the preservation of animal carcasses, but for embalming a human body! It is, however, the exact same process that he demonstrated years earlier in London to Smith at the Society of the Arts meeting on 13 April related to carcass preservation.

From the process description, it is clear that we have identified Morgan, father of the arterial injection method in meat curing as Dr John Morgan, professor of anatomy at the University of Dublin, son of John Morgan, Surgeon to Guy’s Hospital. The original inventor of the system was the Dutch physician, Frederik Ruysch and the application was embalming.

Henry Denny and the claim of a Return to Dry Salting

No review of curing history will be complete without mentioning the legendary Henry Denny and the equally legendary company founded by him.

Ireland in the first half of the 1800s was a fertile field for innovation. An excellent example is found in the person of Henry Denny. Part of his remarkable legacy is a firm that once was the largest bacon producer in Europe, Henry Denny & Sons. Henry was born in Waterford, Ireland in 1790.

Denny started out as a provisioner merchant in Waterford. The first reference to him as a bacon merchant comes to us from 1846. In 1854 he started using ice in bacon curing which allowed him to cure meat all year round like his colleagues in Calne. The bacon he cured was also referred to as mild cured bacon and a patent was granted in 1857 on his process. Like the process invented by C & T Harris, which they called Sweet Cured Bacon, Henry’s process used much less salt. The priority for inventing the first mild cured system, however, goes to William Oake from Ulster whom we know invented this at around the time when Denny had his merchant business or shortly after this and well before Denny entered the pork processing trade.

Henry’s curing system is described in Geocaching where the post seems to be a copy from another work that is unfortunately not referenced and all my attempts to locate the original publication have been in vain. The author describes it as follows: “Until the early 19th century, pork was cured by soaking large chunks of the meat in barrels of brine for weeks. Shelf life was poor, as often as the inside of the chunks did not cure properly, and meat rotted from the inside out. Henry Denny and his youngest son Edward Denny introduced a number of new innovations – he used long flat pieces of meat instead of chunks; and they dispensed with brine in favour of a dry or ‘hard’ cure, sandwiching the meat in layers of dry salt. This produced well-cured bacon with a good shelf life and revolutionised Ireland’s meat industry. Irish bacon and hams were soon exported to Britain, Paris, the Americas and India“.

Reference is made to the fact that Denny invented several curing techniques and if the description given is correct, it would be one of several inventions. Taken at face value I doubt the superiority of his system over Oakes’ invention. It also comes so late in terms of dates that I seriously doubt if this could be the patent that was awarded in 1957. By this time meat injection was already well established which solved the shortcomings of William Oakes’ invention in his mild cured system of simply filling the curing tanks with brine to diffuse into the meat “naturally.” If this was in fact the patent that was granted in 1857, it would represent a serious step backwards.

The greatest contribution to this review article of Denny is the fact that he acquired a meat curing company in Denmark in 1894. The reference is Lets-Look-Again which also seems to quote an uncredited source. They make a statement that this purchase “introduced Irish meat curing techniques to Denmark.” I have over the years come across several authors who made the same claim that the Irish meat curing system was introduced to Denmark in the late 1800s after an Irish firm acquired a Danish processing company. They never gave the name of the Irish firm in question. The end of the 1800s is, however, the wrong time for the introduction of the Irish system to Denmark. By this time it was already well established in Denmark and the likely transfer of the technology to C & T Harris took place from Denmark either at this time (closing years of the 1800s) or in the opening few years of the 1900s. For this reason, I never used the reference but I was always curious about who the Irish firm was, wrongly credited for the transfer of the technology to Denmark. Now I know and for this reason, as well as the widespread nature of the erroneous claim, I include it here.

Denny was undoubtedly a creative man. He is credited with the invention of the pork rasher. Geocaching quotes an unnamed source that “the rasher (a piece of bacon to be cooked quickly or rashed) was reportedly invented in 1820 by Henry Denny, a Waterford butcher who patented several bacon curing techniques still used to this day.” It must be mentioned that Denny’s career only started in 1820 but that was not as a butcher. It was as a merchant and he entered the pork processing business only in 1854. There could still be credibility to the claim which I base on the widespread nature of the story in Ireland. Maybe he was a young man with unusual interest and creativity in selling pork at his trading business. The claim may however be apocryphal.

Related to the inventions of Henry Denny in bacon curing in particular, is there any clue as to what this may have been exactly? It was when I studied the life of another man who claimed to have invented a unique curing system, the Dutch Orthodox Jewish bacon curer Aron Vecht, that I discovered the great contribution to the art of curing made by Denny. One aspect of pork curing that I overlooked for years was the importance of singeing. It is exactly in this area where Henry Denny made his greatest contribution to curing.

Singeing pork was nothing new. Removing the hair off the carcass and retaining the “rind” was done with straws for centuries. The old method is beautifully illustrated by Тихомир Давчев in their set of photos featured below.

Henry Denny automated this process. He re-looked at the process in light of the latest industrialised equipment available. One publication from 1866 describes it as follows. “Each pig is hoisted by the hind leg, it is hooked on to a lever, which suspends the animal head downwards, and its throat is slit with a sharp knife; the blood caught in a receiver flows into an external tank, from whence it is carted away. The leg is then fixed to a hook, which slides on a round iron bar placed overhead on an incline. A push of the hand sends the dead pig with railway speed to the singeing furnace, a distance of 30 to 50 feet. Here it is taken by a crane, placed on a tramway, and run into the furnace, where the flame impinges on it, and in a moment all the hair is removed. The carcass is re-hooked by the leg, passes into another room, where it is disembowelled, the entrails being transferred to an underground region or be dealt with. The head is next removed, and then the backbone is cut out, thus dividing the carcass into two flitches, which pass, suspended on the round bars and without handling, into the cooling room, where it hangs until the meat is firm.” (Fraser’s Magazine for Town and Country, Vol. LXXIV July to December 1866) 

His fame was in the first place due to his invention of the automated process of pork singeing. He may have, of course, also called his process “mild cured” as with the aid of refrigeration he would have obtained the same result as did William Oake who actually invented the original mild cured process.

Was this disingenuous for him to also have called it “mild cured”? I think not. It illustrates the inherent problem in using the result of the process (i.e. milder bacon) as the name of your product. If the result is the same but a different process was used to arrive at it, how would the consumer know (or care)! From a trademark perspective, it makes it tricky since the words seem to be difficult to protect as it would be the general way people would refer to the bacon, not heavily salted. It is like trying to trademark the phrase “well cooked.”

The Dutch Orthodox Jew, Aron Vecht and His Secret Curing System

If we have spoken about Henry Denny, we most certainly have to stop for a minute and look at Aron Vecht who essentially copied the system of Denny and passed it on as his own invention.

Dr James Anderson told me in New Zealand that Vecht claims that worldwide “only five firms possessed the right to use [his secret]’ one of which was his own, the London-based Inter-Marine Supply Company. This means that William Oake’s company, Oake-Woods in Dorset was by far the most widely used curing system under a patent of the time. Still, what Vecht created was impressive.

Vecht took out patents in 1894 in New Zealand related to the singeing of pigs and the preservation of meat. His method of preservation was called the “Vecht Mild Cure Process.” He masterfully tied the patent was tied to his own bacon brand, York Castle. The patents were presumably owned by his business in New Zealand which he had with William Stokes called the Christ Church Meat Company, Ltd. An interview with Vecht in New Zealand from 1894 reveals that the essence of Vecht’s curing system was in fact the system of William Oake and Mild Curing (Interview with Aron Vecht 1894) to which he added the singeing of pigs. Like Oake, Vecht used known systems and fused them to create his own unique curing system. Like the original Mild Cured system, Vecht used sal prunella and his bacon was pale. (Interview with Aron Vecht 1894) This was, however, not the full extent of his system. To this, he added refrigeration!

From a lawsuit following his death related to the York Castle trademark in New South Wales, Australia, we get insight into how he managed his intellectual property. The trademark and his secret method of curing went hand-in-hand. Only the Vecht Mild Cure Process could be used to produce the York Castle brand of bacon. Vecht would receive monetary compensation for every pig so cured in a territory.

When refrigeration was introduced into international trade, its impact on meat quality was an unknown. People opted for the less harsh conditions of chilling temperatures and tried to avoid freezing the meat. A drawback of mild cured bacon is that it did not last on long sea voyages under chilled conditions. The English market has, by the time Aron Vecht arrived on the scene, became used to mild cured bacon as opposed to heavy salted which was the kind of meat produced under the Rapid Cure process of Robert Davison. An attempt was made to use the sea voyage for the curing to take place and to pack the pork on ice. Famously the Harris brothers of Calne were involved in exactly this scheme. The Waikato Argus who reported on this in 1901 said that the lowering of the temperature below 32^o Fahrenheit (0^o C) has ‘invariably faded the flash into a pale, unpleasant colour and alienated the affections of the British matron.” If they achieved the cured colour as we are used to it today, what could have happened is that they meant that lowering it to 0^o C was ineffective in securing a good product that would arrive in London. At chilling schilling temperatures, when the meat has not been heated through hot smoking, the curing colour, resulting from the effect of nitric oxide on the meat proteins, giving it a bright pinkish/ reddish appearance would be reversed. If, however, the meat is frozen, such reversal would not take place. The meat would then be smoked when it arrived at its destination and the colour would be “fixed” through the unfolding of the proteins. They, however, had pale meat, to begin with. (Interview with Aron Vecht 1894)

The Waikato Argus reported on this progression by Vecht as follows: “Now, however, by what may be called a triumph of transit and cure, a most promising and important trade has begun between New Zealand and England. By employing the Vecht curing process, a New Zealand firm is shipping pigs from that distant colony, placing them in refrigerators with a temperature of 20^o Fahrenheit (-6^o C), and curing them here on the banks of the Thames with apparently perfect success.”

It was not well understood at the time and it was incorrectly believed that the method of sterilisation of the meat which was part of the Vecht process was responsible for preventing the cured colour from fading. What is true is not that it would have prevented the cured colour from fading, but that it would have stopped bacterial and enzymatic action which spoiled the meat and degraded the meat quality and this would undoubtedly also have affected the meat colour, even though it was by no means the only reason why the colour faded.

The article reported on this as follows. “This success is obtained by first treating the carcase*, before they leave New Zealand, by the Vecht curing process, which allays the action of the cold, and so sterilises the flesh as to prevent the changes which have hitherto interfered with the successful curing at Home of what is grown abroad.”

The Waikato Argus which we quoted above related to the use of temperature and the curing of meat made also provides us with another very valuable bit of information related to the trading of bacon cured with the Vecht method. It reported that “Messrs Trengrouse and Co., who are colonial shippers on a huge scale and the British agents of Armours, of Chicago, are encouraging this new process, and prophesy for it a vast influence on the bacon trade.” The mention of the agents of the legendary firm of Phil Armour is of extreme interest as is the link between Armour’s company and the propagation of Vecht’s method of curing. Armour was the pioneer of freezer technology for the distribution of meat in America and owned probably the largest curing works in Chicago in the world. Vecht was an expert in the refrigeration of meat in particular. Phil Armour was carefully plotting his way to introduce sodium nitrite directly as a curing brine but not wanting to be left out of the huge and lucrative international bacon trade, must have seen Vecht as a brilliant ally to secure bacon for his own trade while avoiding the expensive curing systems such as Auto Cure which Armour knew would be replaced by the direct addition of nitrite to curing brines.

– Messrs Trengrouse and Co

I told you that the one interesting aspect of Vecht was his method of curing. I referred you to the Waikato Argus which did an article on his life from where we got the all-important information on the temperature during the shipment of the meat. The same article mentions that Vecht’s products were sold through the firm of Messrs Trengrouse and Co.. They are described as colonial shippers on a huge scale and the British agents of the Armour Packing Company from Chicago, who are encouraging his new process. This brings us to the next fascinating aspect of this remarkable man’s life namely his link to the legendary provisions and general commission merchants of Messrs Trengrouse and Co.

The firm was officially called Trengrouse, H & Co., and was described as “Provision Agents and General Commission Merchants” Their address was 51, 55, Tooley Street, London, S.E. The firm was established in 1875 by Henry Trengrouse and his brother, who retired in 1908. They had agents in Liverpool, Manchester, Bristol, Cardiff, Melbourne, Sydney, Brisbane, Dunedin, (N.Z.), Monte Video, Buenos Ayres and they specialised in butter, cheese, bacon, eggs, and canned goods. They claim to have pioneered the trade in New Zealand and Australia in dairy products. Most important for our purposes is that they were the agents for Armour & Co. from Chicago and by 1914 they have been Armour’s agents for upwards of thirty years. (1914 Who’s Who in Business) This means that Phil Armour probably set them up himself and dealt directly with them. Phil passed away at the turn of the century.

The grandfather Henery Trengrouse after whom he was named was a legendary figure in his own right. He devoted his life to the invention of a number of methods to improve safety aboard ships after he witnessed the sinking of a ship with a tragic loss of life close to his home town when he was a young man. (5) Adventure and perseverance ran in the family and, I am sure, accounted for their success in no small way!

– International Bacon War: Quest for Supremacy

I thought it important to deal with Vecht, Trengrouse, and Denny in relation to each other since it speaks to the state of international competitiveness of the newly emerging superpower of the United States relative to the diminishing influence of England. We must not lose sight of the fact that Vecht’s process was a short-lived attempt by the Dutch (Vecht) and the Americans (Armour) to wrestle away control of the international bacon market from the British.

Over the years I have always wondered why Phil Armour did not try and assert his influence on the lucrative bacon trade not just through exports to Britain (which they did on a large scale), but in the international bacon trade. I never came across them in almost 10 years of research apart from sending bacon from the USA to England. This all changed with the mail from Dr Anderson and looking into the life and career of Vecht.

I speculate that their agents found an ideal ally in the Dutch curer, Aron Vecht. Vecht combined several known (and patented) curing processes, created his own version of mild cure, ostensibly predicated upon the use of refrigeration, and an invention by the Irish firm of Henry Denny that automated the singeing process of the carcass. I suspect his allegiance with Armour either led him to become an expert in the newly developing art of refrigeration or he was already interested in this before he came into contact with the Armour Meatpacking company in Chicago. His curing process would have suited Armour in that it was far less capital intensive than Dorset based firm of Oake-Wood’s autocue and despite not being as fast in curing as was accomplished with the autocue equipment, it was a progression on the mild curing process of the inventor of the original process, William Oake, father of the Oake who was a partner in Oake-Woods.

The link with a unique bacon brand is a stroke of genius and something, I am sure, that was carefully deliberated. Before this time, bacon was differentiated by the particular method of curing. As I explained at the start, these would have been dry-cured, sweet-cured, mild-cured, pale-dried, or auto-cured. There is evidence of Harris going after people using the name “pale dried bacon” but the advent of refrigeration, effectively levelled the playing field as many options became available to produce bacon with far less salt than was traditionally done under the dry-cured system.

Another very important point about Armour must be made. A few years ago, I came across a reference to a secret trial in the use of sodium nitrite done at a packing plant in Chicago. The year was 1905. This was done before its use was legal in any country on earth. I speculated that it was carried out by Phil Armour as very few people would have had the audacity to have tried it. I reported on this experiment in an article and shortly after this all references to it were removed from the publications I cited and I could not get hold of the source documents. I know the author of the article where this reference appeared. He is a prominent person in a leading role in European meat-curing circles and I understand why this reference was removed.

This is pure speculation on my part, but it has a tone of credibility. I think that Armour or Armour with the key meatpackers in Chicago of Gustav Swift, and Edward Morris jointly performed the trial. I wrote extensively about this in The Direct Addition of Nitrites to Curing Brines – The Spoils of War. The experiment would have been spectacularly successful and I believe was done on the back of experiments done in German agricultural research centres for years before 1905.

With them having known about the work on nitrites, I believe the process of Vecht suited Armour well as a kind of a “placeholder” without engaging a firm like Oake-Woods and locking them into the Auto Curing system which was the leading system internationally at the time as far as it being patentable and indeed, it was the most widely used international patented system of the late 1800s and early 1900s.

There is an “air” of the thinking of Armour, Swift and Morris in the preamble to a meat science group formed by them, also in the early 1900s where their mission was stated as being “to reduce steers to beef and hogs to pork in the quickest, most economical and the most serviceable manner.” The process they had in mind here was nitrite curing.

It was a key turning point in the history of curing and the Americans spectacularly took the lead when, following the first world war, Griffith, the American Chicago-based company became the evangelist of the direct addition of nitrite to curing brines, a riveting saga which I uncovered and wrote extensively about in the article which I just now sited. So, anticipating what is to come in the direct addition of nitrites to curing brines, there would have been no point in investing in any of the “indirect curing processes” of the English, Danes, or the Dutch. There is evidence that the Chicago meatpackers were preparing for this curing revolution for a number of years and the Griffith Laboratories was an important participant who had to be ready to handle the PR of what was to come. They have undoubtedly taken careful note of public perception related to nitrites and had to be careful how they introduce the matter to the public. Besides this, they had to ensure that using nitrites directly in meat curing was legalised. All this was carefully orchestrated and it completely explains why they never fully committed to curing systems that dominated through the rest of the world prior to 1905. Supporting the Vecht system would have been a perfect “placeholder.”

Was the use of the curing technique of Vecht as deliberate as I present it here? I suspect it but have no direct evidence to that effect. Is it a likely scenario, taking the full spectrum of information from that time into account? I believe so! At least it warrants keeping the possibility in mind as we progress our efforts to understand the grand story of the development of bacon!

Drying and Smoking of Bacon

Another aspect of bacon processing that we have not considered thus far is the drying and smoking of bacon. The oldest reference I can find of the smoking of bacon is a statement by the Scottish farmer, Robert Henderson that he created his own very simple design for a smokehouse in 1791. (Robert Henderson and the Invention of the Smokehouse) What is interesting about his account is that it deals with the establishment of the pork trade in Scotland.

Henderson recalls that in 1766 pigs were brought into Annandale in Scotland for the first time. Farmers bought them more out of curiosity than to make a profit. The pigs were small with bristles on their back. Between 1775 and 1780 both bacon flitches and hams became a considerable trade in this part of Scotland. By 1790 the pork trade was well established with buyers travelling throughout the region to buy pigs. Several markets were established for pigs. One such market was established at Dumfries where the Annadale curers meet the Galloway farmers. Events allowed Robert a birds-eye view on the birth of an industry!

Robert Henderson was a formidable pork trader. He distributed the carcasses among the farmers to dry and smoke them in the farmhouses. In one season he would cure no less than 500 animals in this way. He wrote, “I practised for many years the custom of carting my flitches and hams through the country to farm-houses and used to hang them in their chimneys and other parts of the house to dry, some seasons to the amount of 500 carcasses.”

The system was accompanied by many difficulties. For starters, he often had to provide his own wood for hanging the flitches and hams on. This was only the start of the trouble. He wrote, “for several days after they were hung up, they poured down salt and brine upon the women’s caps, and now and then a ham would fall down and break a spinning wheel, or knock down some of the children; which obliged me to resort to the shop to purchase a few ribbons, tobacco, &c. to make up peace.”

The biggest problem of this system is related to weight loss. Henderson wrote, “there was a still greater disadvantage attending this mode; the bacon was obliged to hang until an order came for it to be sent off, which being at the end of two or three months, and often longer, the meat was overdried in most places and consequently lost a good deal of weight.”

In 1811 Henderson noted that this was still the way that bacon was cured in large quantities in Dumfriesshire. He lamented the fact that people are slow to abandon old ways of doing things in favour of better alternatives.

Robert Henderson claims that twenty years earlier, in 1791, he designed a simple, dedicated smokehouse for smoking hams and bacon. This simple statement would become my earliest reference to a smokehouse. He describes it as being twenty feet square (1.8m²) with walls about seven feet (2.1m) high. Each wall allowed for 6 joints. Twenty-four flitches can be hung together in a row without them touching. Each one of the flitches was resting on a beam. There are five rows, allowing for a total of 120 flitches in the smokehouse. The flitches were hung between 2¹/₂ to 3 feet (900mm) from the floor which is covered with sawdust of five or six inches (100 to 150mm), kindled at two different sides. (Henderson, 1811)

The door is kept closed with a small hole in the roof for ventilation. Bacon and hams smoked in this smokehouse were ready for dispatch within eight to ten days. An advantage of this system is that there is only a little loss in weight. (Henderson, 1811)

So, the system was that the bacon was kept in the salt-house till an order is received. At this point, it was moved to the smokehouse for drying and smoking before it was dispatched to the client. (Henderson, 1811)

During this time, the invention of the smokehouse by Robert Henderson had a dramatic impact on the quality of the bacon. One of the consequences of too much drying is very salty meat since water escapes, but salt is left in the meat.

This invention was “in the air” already since Henderson’s 1791 invention of the smokehouse. Losing weight results in more salty bacon as a large weight loss reduces the volume of meat to salt, making the remaining meat saltier. Smoking, at this time, was exclusively cold smoke.

Apart from better-tasting bacon, there was a significant reduction in cost. Henderson wrote that he “found the smoke-house to be a great saving, not only in the expense and trouble of employing men to cart and hang it through the country, but it did not lose nearly so much weight by this process.”

It is extremely unlikely that Robert Henderson was the first or only person who did away with the farmhouse-drying/ smoking of hams and bacon and opted for a built-for-purpose smokehouse. The following hundred years would see a plethora of ideas being shared and taken up by various companies and individuals, many claiming priority for their invention or progression. It is possible to get close to the people who pioneered these different progressions based on the dates for their inventions but if we are ever able to identify the very first person related to each invention is highly unlikely. It is, however, fascinating how close we can get to the first instance of an invention or progression.

It is interesting that the 1791 reference of Henderson (when he first designed his smokehouse) is still the earliest reference we can find anywhere to smokehouses. Following the indirect reference of Henderson, the next reference I was able to find was a 1796 reference to a smokehouse being part of an estate for sale. (The Philadelphia Inquirer, 1796) Several advertisements for properties in Pennsylvania with smokehouses on occurred in the 1790s and into the early 1800s. There is an 1813 reference to a smokehouse by a reader who complains that his measures against insects are not working. (Buffalo Gazette, 1813)

An 1820 account from Newbern Sentinel (New Bern, North Carolina), 1820 is my first reference where smoking and drying are specifically separated.

The author elaborates on the experience of his teacher who warned him about damp which leads to bitter-tasting bacon. He uses an interesting phrase to describe Mr A of Baltimore namely a man who “followed smoking for gain.” He is therefore squarely set in a commercial mindset.

The author continues. “one good fire per diem will smoke the pieces exactly in the same time they were salted viz. hams 4 weeks, shoulders 3 weeks, other pieces in two. When the bacon is smoked and all returned to the smokehouse, a floor, if not laid before should now be laid on the joist; by this means rats will be prevented from descending on the bacon, and the heat of the sun will be moderate so that the bacon will not drip in the summer heats. Darkness and coolness are necessary to preserve the bacon from flies – it may there hang in perfect safety till wanted!” (Newbern Sentinel (New Bern, North Carolina), 1820)

The fact that smokehouses were a new progression in the 1840s is seen from a newspaper report from Northern Ireland in 1841. The article points out that due to the misconstruction of the smokehouse and because the surface of the meat is not properly wiped dry and there is still saline matter on the outside of the meat, these cause the meat not to dry out but remain moist. Because of this a “pyroligneous acid taste and smell” is left on the meat.

The author gives the requirements for a good smokehouse:

• it should be perfectly dry;
• not warmed by the fire that makes the smoke;
• the fire shall be sufficiently far from the meat so that any vapour from the smoke shall be “thrown off” and may be condensed before reaching the meat;
• yet, close enough to prevent flies, mice, etc from feasting on the meat.

The art of building a proper smokehouse was still being disseminated through the British Isles by 1841. Not only in Britain but also in Germany smokehouses were not universally used to smoke bacon. The same article refers to smoking meat in Westphalia. Smoking Westphalia hams was done at this time in “extensive chambers in the upper stories of high buildings, some of four or five stories.”

In the constructions in Westphalia, the fire was made in the cellar and the smoke directed to the meat through pipes in which the heat was absorbed and the moisture removed. The smoke was dry and cool when it came into contact with the meat. The meat is, in this way, perfectly dried and had a flavour and a colour far superior to meat smoked in the “common method.” (Belfast News-Letter, 1841) Westphalian bacon and hams were notorious for what was later referred to as cold smoking. For a detailed discussion on this, see Westphalia Bacon and Ham & the Empress of Russia’s Brine: Pre-cursers to Mild-Cured Bacon.

The strict aversion to heat of any kind in the smokehouse would not last and subsequent authors and experts found that a bit of heat produces a better environment for drying (less moist).

There is a reference from Lancaster Intelligencer (Lancaster, Pennsylvania), 1833 which states that during smoking the smokehouse should be warm but after smoking, it should be cool and dark. This “heating” of the smokehouse is an interesting reference and was by no means universally practised as we saw from the construction of the smokehouses as described from Westphalia. Another report from 1840 states that the smokehouse should be of a moderate temperature. The purpose is given as it will prevent dampness on the meat. (New England Farmer, 1840)

Heuzenroeder (2006) reports that the Westphalia method of cold smoking became the norm in Germany. “German hams were smoked, often in a series of ingenious smoking chambers or racks high up inside the chimney cavity to hold the smallgoods. Every house in growing German cities in the 1800s had smoking chambers on an upper floor with cool smoke ducted from fireplaces in rooms below. Old farmhouses devoted much space to smoking meat. The Brandedburgisches Freilichtmuseum, Altranft, Germany, has restored a farmhouse with a traditional Schwarzeküche or “black kitchen,” where the entire room in the centre of the house contains the cooking hearth. Above the whole room rises the interior of the chimney with hooks and rods for smoking meat. Notes on the restoration website say that this was the typical structure of a middle-sized Brandeburg farmhouse before 1800. (Heuzenroeder, 2006)

The Harris operation would progress this concept years later when they invented pale dried bacon where the bacon is dried in specially constructed ovens but not smoked (Harris Bacon – From Pale Dried to Tank Curing!)

– Smokehouse as the Storeroom for Finished Bacon

One system of storing the bacon was to keep it in the salt house till its sold. Then, smoke it and dispatch it to the client. Another system was to use the smokehouse as the storeroom for finished bacon. The system described in Winchester, Tennessee in 1856 calls for the bacon to be removed from the curing vats and the salt to be scraped off. Rub the bacon all over with hickory ash and hang it up for smoking, hock down. Smoke moderately for four weeks with only two fires a day made from hickory chips. On about the 1st of March, take them down, rub them with hickory ash again and hang them again. Here they remain the whole year. It makes an interesting comment that if little green mould appears on the outside of the bacon, it only ensures against spoilage. (The Home Journal (Winchester, Tennessee), 1856)

The hams and bacon can be wrapped in cotton bags for storage during the summer. Before use, dip the bag in strong salt brines to protect against insects. The next season, while bacon and hams are being smoked, hang the cotton bags in the middle of the smokehouse. The smoke will preserve the cotton.

During the summer, the bacon should not be hung against the roof, due to the heat, but in the middle of the smokehouse where it is cooler. The smokehouse should be dark, and in the summer, the ventilation holes must be closed to keep insects and rodents out.

– Was this customary in Wiltshire in the 1840s?

In asking this question, we look one more time at the possible nature of sweet-cured bacon invented by Harris in the 1840s. (Sweet Cured Harris Bacon) An article from the Yorkshire Herald and the York Herald (1840) reports on the following method of curing used in Hants, Wilts, and Somerset.

The pork is singed by packing straw around the carcass and burning the bristles, and hair off. Scalding tends to soften the meat and this method ensures the meat is left firm. The carcass is left to cool after which it is cut into flitches and salted and treated with saltpetre. The flitches are left for two to three weeks and turned three to four times. They are then wiped dry and suspended over a chimney over a wood or turf fire to dry out. A note is made that coarse sugar is used in Hampshire bacon but not in Wilts and Somerset. Hampshire bacon is imported with its particular flavour by the wood and turf smoke. During smoking, the flitches must be taken down and inspected for bacon-fly.

The 1840 newspaper report does not claim to be exhaustive, but it nevertheless creates the picture of a simple non-industrialised process and most certainly there is no mention of a dedicated smokehouse or salt house. In a dedicated butcher shop, as was run by the Harris family, one would expect a smokehouse and a curing room.

– Comparisons with William Oakes Mild-Cured Bacon

We dealt with the mild cured system of William Oake in great detail (William Oakes Mild-Cured Bacon) and since he invented what later became known as tank curing, it is important that we reference his system again.

The first major difference with what we have seen so far relates to drying. Instead of hanging the bacon to dry, Oake used pressure when he re-stacked the flitches after curing, on a dry floor. The weight of the bacon is incrementally increased as the flitches are re-stacks with the ones at the bottom now on the top and by stacking them higher and higher every time it is restacked while always rotating the position of the meat pieces.

Oake called for a quick smoking of the bacon. According to his system, between twenty-four and forty-eight hours will suffice to properly smoke the bacon if the weather is suitable, after which it may be packed and forwarded to market.” His smokehouse design is in line with what we have looked at thus far. He also used cold smoke.

Pale Dried Bacon and Wiltshire Cure or Tank Cured Bacon

The next major development in curing also came from C & T Harris (Calne). Pale Dried Bacon was invented by them just before they adopted tank curing. It was invented under John Harris in Calne in the 1890s. It is basically the same as Sweet Cured Bacon but instead of hot smoking the bacon, it was dried in special drying rooms and not smoked. The bacon was therefore pale on the outside of the flitches but it was properly dried. From there the name Pale Dried Bacon.

It was just after this, at the closing years of the 1800s or the very first few years of the 1900s that tank curing technology was transferred from Denmark to Calne in Wiltshire. The technology of mild cured bacon of Oake, invented in Ireland, adopted by the Danes finally spread to Calne, Wiltshire and became the famous British Wiltshire bacon curing or Tank curing in the closing years of the 1800s or early 1900s. For a detailed discussion, please refer to Harris Bacon – From Pale Dried to Tank Curing.

Wet-curing in combination with injection (brine cure – with pumping)

The first cooperative bacon-curing company was started in Denmark in 1887. It was seven years after the visit to Waterford in Ireland in 1880 “taking advantage of a strike among the pork butchers of that city, used the opportunity to bring those experts to their own country to teach and give practical and technical lessons in the curing of bacon, and from that date begins the commencement of the downfall of the Irish bacon industry. . . ” (Tank Curing was invented in Ireland)

It means that the Danes had the technology and when the impetus was there, they used the technology. The impetus, as we already said, was the outbreak of swine flu which saw a ban on Danish pork. They had no choice but to change their export from live pigs to bacon. The detailed description of Oakes invention and his process came to me through an Australian publication from 1889. It means that Ireland not only exported the mild cure or tank curing technology to Denmark but also to Australia, probably through Irish immigrants during the 1850s and 1860s gold rush, between 20 and 30 years before it came to Denmark. Many of these immigrants came from Limerick in Ireland where William Oake had a very successful bacon-curing business. Many came from Waterford. A report is given in The Journal of Agriculture and Industry of South Australia, edited by Molineux, General Secretary of Agriculture, South Australia, Volume 1 covering August 1897 – July 1898 and printed in Adelaide by C. E. Bristow, Government Printer in 1898. Apart from giving the complete system as invented by Oake and crediting him for the invention, it also sites one company that used the same brine for 16 years by 1897/ 1898 which takes tank curing in Australia too well before 1880 which correlates with the theory that immigrants brought the technology to Australia in the 1850s or 1860s.

One further note about the invention of tank curing by Oake from Ireland. He was a chemist and his invention had as much to do with the brine makeup as it had to do with the fact that tanks were used. Morgan’s work, already cited in great detail here, shows clearly that curing brine was a priority in Ireland in the mid-1800s. The possibility that Oake and Morgan interacted and possibly influenced each other is a tantalizing likelihood that emerges from the data.

It was Denmark, however, who continued to expand on the tank curing system, or mild cured system, as it was called, using a combination of stitch pumping and curing the meat in curing tanks with a cover brine.  (Wilson, W, 2005:  219) Brine consisting of nitrate, salt, and sugar was injected into the meat with a single needle attached to a hand pump (stitch pumping). Stitch pumping was either developed by Morgan, whom we looked at earlier, or became the forerunner of arterial injection which is solely credited to Morgan.

The meat was then placed in a mother brine mix consisting of old, used brine, and new brine. The old brine contained the nitrate which was reduced through bacterial action into nitrite. It was the nitrite that was responsible for the quick curing of the meat. 

The Auto Cure System and the legendary Oak Woods & Co. Ltd. Bacon Curer

The auto cure system is an excellent example of the fact that the power of the used brine was known and who else to have invented it than the son of the man who pioneered the live brine system, namely Willaim Oake! 

William Horwood Oake set his curing operation up in Gillingham, Dorset with partners. It eventually became the famous Oak’ Woods & Co Ltd. Oake invented the system which was eventually in use in England, Sweden, Denmark, and Canada. William Harwood Oake passed away on 28 September 1889 in his late 40s and Evan R Down took over the running of the company. There is a report that they exported their technology to New Zealand and South Africa also. They patented it around the world and licensed its use to companies in different countries. Down became the driving force for international expansion on the back of solid patents. The Danes paid a £4,000 annual royalty for the use of the system which was probably applied in many factories across Denmark. They became the premium representation of Wiltshire bacon meaning the curing of whole bacon sides.

The process is as follows. The pig is slaughtered in the usual way and the sides are trimmed and chilled. After chilling, it is laid out in rows on a sort of truck that exactly fits into a large cylinder of steel 32 feet long, 6 feet in diameter, and which will hold altogether 210 sides. When the cylinder is filled, the lid, weighing 3 ½ tons (7000lb. Danish) is closed and hermetically sealed by means of hydraulic pumps at a pressure of 3 tons to the square inch.

A vacuum pump now pumps all the air out, which creates a vacuum of 28 inches. It takes about an hour to pump all the air out. The brine channel which leads to the brine reservoir, holding around 6000 gallons of brine is now opened. The brine rushes into the chamber and as soon as the bit of air that also entered has been extracted again, the curing starts.  It happens as follows.

The brine enters the cylinder at a pressure of 120 lbs. per square inch. It now takes between 4 and 5 hours for the brine to enter the meat completely through the pores, which have been opened under an immense vacuum. When it’s done, the brine runs back into the reservoir. It is filtered and strengthened and used again.

An advantage of the system is given that the bacon can then be shipped overseas immediately. The time for total process is around three days. On day 1 the pig can be killed, salted on day 2, and packed and shipped on day 3.

There are two brine reservoirs. The one is used with a stitch pump to inject brine into the sides as usual before they are placed in the cylinder and the second tank is used. The largest benefit of this system is the speed of curing and many people report that the keeping quality of the bacon and the taste are not the same as bacon cured in the traditional way.

For a full discussion on the father-son duo of William and William Horwood Oake and their inventions, see William and William Horwood Oake.

American Rapid Curing

Auto Curing was, however, only a progression of the Rapid Curing system developed in America.

Clues as to the possible origin of the American report come to us from an 1848 report in the Sydney Morning Herald. The author begins his explanation of a certain American curing system with an interesting statement. He says that “they (we) desire considerable satisfaction in promulgating the discoveries and inventions of our fellow labourers in the field of science, no matter whether they be transmitted to us from the shores of the Neva or the banks of the Mississippi, and we, therefore, hasten to lay before our agricultural friends an important American invention, which promises to with the greatest benefit in a particular branch of the domestic economy, as well as in a commercial point of view, and which we are certain requires only to be generally known to be usually adopted.” (Sydney Morning Herald, 1848) In this, the author is completely right that adopting and adapting inventions are, for the most part not very difficult. It clues us into something of the possibility that Auto Curing may well be an improvement of an American invention.

The author then turns his attention to a certain Mr Davison. Setting the 1848 report in the Sydney Morning Herald aside for a moment, we see if we can find evidence of who this Mr Davison was. A stunning description is given by Paul (1868) who records that Mr Robert Davison attended the food committee meeting as a member of the Institution of Civil Engineers, in order to give information on the subject of desiccation as a preservative process which he studied since 1843. So, here we have Mr Davison’s first name given as Robert. He was an engineer by profession and he has been studying preservation since 1843. It definitely looks like the right man!

Paul (1868) gives us more information. He was not originally from the USA but resided in London. He writes that Robert was of No. 33, Mark Lane, in the City of London, Civil Engineer, and James Scott Horrocks, of Heaton Norris, in the County of Lancaster, registered a patent for improvements in the means of conveying and distributing or separating granular and other substances.” The patent was sealed.

Paul then explains the basis of Robert’s method of preservation being through heated air and using the newly emerging science of creating a vacuum. “The importance of hot blast had been discovered in the melting of metals, and it occurred to him that impelled currents of hot air might be advantageously applied to other processes of manufacture, especially as a purifying and desiccating process. In reference to its application to the purification of brewers’ casks, the question arose, in the first instance, as to the effect it would have upon the strength of the wood.” Here we pick up the similarities of Oake’s Auto Cure system with treating wood. “He (Robert) experimented on the subject and found that, so far from deteriorating the wood, it gave increased strength to it to a large extent. He saw that impelled currents of hot air were a valuable thing that had been overlooked, and he then turned his attention to the desiccation (the preservation of food by removing moisture) of vegetable and animal substances.

The key first observation is that his interest was in the removal of moisture and the application of heated air. You may very well wonder how on earth he brought those two together, but hang on. He did it in an interesting way. Paul (1868) writes that “he was successful in the first instance in desiccating potatoes and other table vegetables, which were preserved for a very long time; and he afterwards operated upon a quantity of rump steaks, and by depriving them of all their moisture, they were preserved in a perfectly sweet and wholesome condition for several months.” So far it sounds like standard drying and hot air would not be required. In fact, any air velocity would aid the evaporation process as is done today with fans, for example, in producing biltong. But using hot air, which is moved around sounds very similar to what we use in smoking/ drying cabinets today where the air is indeed warm.

For all South African biltong lovers and American Jerky fans, he reveals something extraordinary. Paul (1868) writes that “at the time he was engaged in these experiments an intelligent young man, brother-in-law to Dr Livingstone. . .” Dr Livingston was of course the famous African explorer missionary who resided at the Cape for some time and laboured mostly in Botswana. He had an intimate knowledge of indigenous drying practices and the value of salt.

Paul (1868) continues describing the relationship with the brother-in-law of Livingston and Robert. He does not focus on information about the indigenous practice from Southern Africa but from North America, even though I am absolutely certain that he would have informed Robert about the drying techniques in Southern Africa also. He mentions that Livingston’s brother-in-law was “then his pupil, mentioned to him that he was doing by an artificial process precisely what the North American Indians did with their buffalo meat and venison by the natural heat of the sun in preserving their provisions, and at the same time, he gave him an extract from Catlin’s work on the subject. The Indian method of drying their meat was to cut it up into thin strips, which were hung upon the branches of trees for several days in the heat of the sun. The moisture was entirely evaporated. The meat was then stowed away and would keep good for years. Salt they never used, notwithstanding the country abounded with it. What the Indians did by natural means, he did by artificial, by the employment of impelled currents of heated air. He cooked some of the steaks desiccated by this process three or four years after they had been operated upon, and they were perfectly good and retained their flavour. After it had been soaked in water the meat recovered nearly its original bulk. In the process of desiccation, nothing but the water was removed, the albumen being all retained in the meat.” (Paul, 1868)

Take special note of his views on the nature of what causes spoilage in meat and vegetables. “By depriving them of all their moisture, they were preserved in a perfectly sweet and wholesome condition for several months.” Mr. Davison said that “he had not entertained the idea of preparing meat in this way (through drying) for the tables of the gentry, but his idea was to have the meat cut into thin slices, thoroughly dried, and packed away for use as we should biscuits. In this way, he thought an excellent article of food might be prepared for shipping purposes and for the poorer classes.” Not just is it clear that he targeted the moisture of the meat but also his method of work required cutting the meat into smaller cuts and inserting it into the apparatus manually which is similar to what the Indians (and the tribes of Southern Africa) did in cutting the meat into strips before hanging it.

“Mr Davison remarked that three or four years ago an article appeared in the Times, expressing a hope that some plan would be devised for desiccating meat in a better manner than had hitherto been done. The results of the process he had described were decidedly superior to any charqui (drying of meat) that he had seen. He had long since parted with the last portion of the steaks he had experimented upon. The apparatus for desiccation was at present largely in use for other purposes, such as the seasoning of the wood, the purifying of casks, &c. It was extensively used for the former purpose in the royal dockyards. He had no doubt he should be able to make the experiment for the satisfaction of the Committee and should have great pleasure in doing so at the earliest opportunity. The heat of the air in his experiments was 180°, but he believed the desiccation would be effected equally well at a temperature of 120° when the albumen would not be coagulated.”

Let’s now park Davison’s views of preservation which we know he worked on since 1843 for a minute and return to the Sydney Morning Herald’s 1848 article. Davison is described as, “prior to his present occupation, was long connected with the manufacture of salt.” We also learn that he resided in South America for a time, in a country “with greater capacities for the production of the hog and the ox” and his attention was turned to the preservation of meat. Mr Davison drew upon his knowledge of salt and after much investigation invented a method of curing that will sound very familiar to us. He is described as possessing an “inventive genius,” well educated and assisted in the matter of science by Dr Lardner, “whom he consulted upon his arrival in the United States.” (Sydney Morning Herald, 1848)

So, we learn that he did travel to the United States and there he solicited the assistance of a certain Dr Lardner. He was an authority on the subject of steam engines and the application of steam in industry.

From William Douglas & Sons Limited, 1901, Douglas’s Encyclopedia, University of Leeds. Library.

Peters (1846) describes the system as follows: “The apparatus is very simple, consisting of a cylinder made airtight. It has a “mouthpiece” through which meat is loaded into the machine and closed with a lid that is screwed onto the machine. The lid has two air vents which are opened and closed by screws. Next to the machine is a large wooden vat holding the brine, connected to the machine through a pipe and elevated higher than the cylinder. A lifting pump circulated the brine from the cylinder back to the vat.” I imagine it looking something like the apparatus at the top of the three above which were associated with Auto Curing.

“Meat is cut and placed into the cylinder. Brine is allowed to fill the cylinder which is then closed. Brine is now pumped back into the vat till all the brine is out and a vacuum is formed in the cylinder with the meat pieces in. Blood, air, and gasses are thus removed from the meat also. Brine is now run back into the cylinder. The air vents are opened and the liquid brine expels all air from the vessel. As soon as the vessel is full, the air vents are closed again, the brine is pumped into the vat again and the meat is left in a vacuum. Again, blood, air, and gasses are pumped out. The cycle is repeated. The initial intervals between the cycles are short but eventually, as all the blood, air and gasses have been removed from the meat, the brine is allowed to remain in the cylinder for as long as between 6 and 8 hours. The entire process is completed in about 12 hours.”

It is here where the explanation or the link that Davison found with meat curing and preservation moves from the factual to the fanciful. He believed that the blood, air, and gasses in the meat created some kind of a “resisting power” to the brine which had to seep into the meat. The blood had an affinity for the brine and left the meat for brine to fill it. The pressure created by the elevated brine created relative pressure greater than the gasses and air. When the meat is under vacuum, the reporter writes that the meat is “swollen, its fibre distended and pores open and it readily admits the brine even at the pressure of the mere quantity of brine which the cylinder will hold.” One atmosphere was sufficient and where double and triple were used, it would respectively close and completely close the pores.

So, he abandoned the use of hot air and instead used a vacuum and the pressure of the brine. Whether his explanation is accurate or not, his invention worked. The process cures the meat in hours as opposed to weeks and he patented it. The process is named Rapid Cure.

This means that Mr Davison’s invention or the application of a vacuum and pressure in curing has priority in terms of the Oake Woods invention which is a progression of the Davison invention. In all likelihood, what Ewart refers to in his 1878 publication is the American invention that was widely in use in America. The key object of the invention was the speed of curing and not the production of mild cured bacon as was the case with the Oake Woods patent.

The primary method of obtaining “mild cured bacon” from the USA was through the addition of sugar. Ewart writes that “it should, however, be stated, that American bacon, in its several forms of flitch, roll, and ham, and any of them of small and moderate weights, are also mildly cured in which sugar is in a considerable proportion an ingredient in the curing mixture used; and the article when so prepared is deservedly held in the highest esteem.” (Ewart, 1878)

Ewart also reports the formation of a bluish-green mould upon the flesh-cut portions of the flitches and hams from bacon or ham that are “perfectly cured and becomes thoroughly dried.” He states that the mould “most effectually prevents the rusting of the fat on these parts.” (Ewart, 1878)

It is clear that Aoto Cure for the meat industry is a progression of Rapid Cure, developed by Mr. Robert Davison which had huge success in the USA. Auto Cure quickly developed an impressive list of countries that participated in the technology.

Tank Curing

For a detailed treatment on tank curing or Wiltshire curing, please refer to The Wiltshire Cut.

Denmark was, as it is to this day, one of the largest exporters of pork and bacon to England. The wholesale involvement of the Danes in the English market made it inevitable that a bacon curer from Denmark must have found his way to Calne in Wiltshire and the Harris bacon factories. The tank-cured method, as it became known, was adopted by C & T Harris (Calne). The fact was that it was already in Wiltshire in the company Oake’ Woods & Co. Ltd.. Why it took C & T Harris till the second half of the 1800s to incorporate it into their processes is a good question to which I don’t have the answer yet.

A major advantage of tank curing, as it became known in England, is the speed with which curing is done compared with the dry salt process previously practised. Wet tank curing is more suited for the industrialisation of bacon curing with the added cost advantage of re-using some of the brine. It allows for the use of even less salt compared to older curing methods. One of the biggest advantages was, however, the increased curing speed as nitrites were used which were already converted from nitrates through bacterial fermentation.

The question comes up if we have corroborating evidence that Denmark imported the Irish technology in 1880. Clues to the date of the Danish adaption come to us from newspaper reports about the only independent farmer-owned Pig Factory in Britain at that time, the St. Edmunds Bacon Factory Ltd. in Elmswell. The factory was set up in 1911. According to an article from the East Anglia Life, April 1964, they learned and practised what at first was known as the Danish method of curing bacon and later became known as tank-curing.

A person was sent from the UK to Denmark in 1910 to learn the new Danish Method. (elmswell-history.org.uk) The Danish method involved the Danish cooperative method of pork production founded by Peter Bojsen on 14 July 1887 in Horsens. (Horsensleksikon.dk. Horsens Andelssvineslagteri)

The East Anglia Life report from April 1964, talked about a “new Danish” method. The “new” aspect in 1910 and 1911 was undoubtedly the tank curing method. Another account from England puts the Danish invention of tank curing early in the 1900s. C. & T. Harris from Wiltshire, UK, switched from dry curing to the Danish method during this time. In a private communication between myself and the curator of the Calne Heritage Centre, Susan Boddington, about John Bromham who started working in the Harris factory in 1920 and became assistant to the chief engineer, she writes: “John Bromham wrote his account around 1986, but as he started in the factory in 1920 his memory went back to a time not long after Harris had switched over to this wet cure.” So, late in the 1800s or early in the 1900’s the Danes imported the Irish system and practised tank-curing which was brought to England around 1911. The 1880 date fits this picture well.

It only stands to reason that the power of “old brine” must have been known from early after wet curing and needle injection of brine into meat was invented around the 1850s by Morgan. Before the bacterial mechanism behind the reduction was understood, butchers must have noted that the meat juices coming out of the meat during dry curing had special “curing power.” It was, however, the Irish who took this practical knowledge, undoubtedly combined it with the scientific knowledge of the time, and created the commercial process of tank curing which later became known as Wiltshire cure.

Why the system was brought over from Denmark when William Harwood Oake’s dad invented the system in Ireland remains a very good question. It is almost impossible to speculate on what exactly was happening in the Harris, Oake ‘ Wood & Co Ltd and in the St. Edmunds Bacon Factory Ltd., but I have a suspicion that Oake Wood was completely focused on their auto cure system in the 1890s and early 1900s and other companies were looking for a less expensive and equally efficient system which the Danish tank curing offered them. I can on the one hand understand why competitors were reluctant to buy into the Oake Wood system of auto curing and on the other hand, why Oake ‘ Woods was reluctant to sell it to strong opposition.

What we know for certain is that tank curing undoubtedly developed from the Oake Woods factory in Gillingham, Dorset, and “diffused” into Wiltshire. It was probably independently incorporated into the Harris operation as was the case with the St. Edmunds Bacon Factory Ltd who both claim to have received the technology from Denmark.

Multi-Needle Injection and Vacuum Tumbling and The Direct Addison of Nitrites to Curing Brine

The composition of the brine changed around 1915 with the direct addition of sodium nitrite. For a thorough discussion on this revolutionary development, see,

• The Direct Addition of Nitrites to Curing Brines – the Master Butcher from Prague.
• The Direct Addition of Nitrites to Curing Brines – The Spoils of War.

Where tank curing used the fermented brine which after fermentation contained nitrites, despite the fact that only nitrates were added to the brine, to begin with, along with salt and sugar, nitrites became widely available through pharmacies at this time as it was used in treating certain heart-related ailments. Nitrites were now being included directly into curing brines, bypassing the fermentation step.

Multi-needle injectors and vacuum tumblers became commonplace in any met curing operation. It is generally accepted that these developments took place in the mid to late 1900s, but an interesting US patent (number 23,141) was awarded to L. M. Schlarb from Allegheny, Pennsylvania on 3 June 1901 directly related to injection and vacuum machines for meat curing.  (Journal of the Society of Chemical Industry; 1902: 269)

The process is described as “injecting brine and carbon dioxide under pressure into the meat by means of suitable needles connected to a tank containing the brine and carbon dioxide, the pressure in the tank being about 2 atmospheres.” The nozzles it talks about may be the three-needle injectors that were used until the middle of the 1900s and the unique aspect of the patent was the use of brine in conjunction with carbon dioxide. (Journal of the Society of Chemical Industry; 1902: 269)

The next bit is fascinating as it is possibly the earliest recorded date of the use of a vacuum machine in meat processing. The patent is described in a journal article as “the meat is now placed in a vessel from which the air is exhausted, and brine is then allowed to flow in. The meat is allowed to remain in the brine for about 10 hours, and may then be subjected to the action of carbon dioxide under pressure.” If one removes the presence of carbon dioxide, it is then reasonable to assume that a vacuum machine has been in use in one shape or another to facilitate the diffusion of brine into meat, as early as 1901. (Journal of the Society of Chemical Industry; 1902: 269) The process was, however, not new as auto-curing was already in use in the second half of the 1800s in many countries across Europe.

Over the next 60 years, the multi-needle injector became bigger, with more needles until the present machines were being produced from the mid-1900s. Tumbling machines, as we know it today has been in use since the early 1970s.

Current Developments

Three major developments are currently taking root across the globe and the last one has the potential to change the way that bacon is being cured. One is a return to fermented brines where a natural carrier of nitrates is used as the start of brine preparations. A starter culture is then added to this “carrier” which will be something like celery powder or beetroot, high in nitrates and specially grown with high nitrate content in the soil. Salt and phosphates, where permitted, are added along with reducing and non-reducing sugar to complete the modern curing brines. This seems like a new curing system, but as we have seen, it is the resurrection of a curing method probably as old as humanity itself. Leafy green vegetables, spices, and many other plants are replete with nitrates and have been used in various forms to cure meat for millennia.

The second important development in commercial curing plants of the last decade is undoubtedly the introduction of what we call the grid system. According to this method, grids or bacon moulds are used to give the bacon a regular shape. The meat is normally wrapped in banking paper or some film before it is placed in the moulds and in one form or the other, an enzyme, Transglutaminase, is added to the product. The main purpose of this is to achieve higher slicing yields, but in reality, it also accounts for lower smoking losses. A detailed treatment of this method can be found at The Best Bacon System on Earth. I am inviting producers who are interested to interact with me on the process as long as developments will be used for our mutual benefit.

The third new development is about to make its entrance onto the bacon curing scene and it is this discovery that makes me particularly excited to be right at the forefront of the investigations and attempts to understand it and commercialise it. It is the use of bacteria that has the ability to oxidise certain nitrogen-containing components in meat to create nitric oxide directly which then cures the meat. Let’s spend some time looking at this development.

Bacterial Fermentation Curing

In a 2017 review I did on the curing reaction, Reaction Sequence: From nitrite (NO2-) to nitric oxide (NO) and the cooked cured colour, I quoted Morita et al. as referenced by Gasasira (2013), who found that nitric oxide (NO) formation in nitrite-free system is achieved from L-arginine due to nitric oxide synthase (NOS) in either Staphylococci or Lactobacilli.  (Gasasira, et al, 2013)  The nitric oxide-producing enzyme in cells is called nitric oxide synthase (NOS), which converts L-Arginine into L-Citrulline and nitric oxide (NO).

This simple statement opens up the world as far as nitrite-free curing is concerned. I was doing a review of this matter again on the night of 24 June 2022 when the gravity of the work of Morita (1998) on the subject dawned upon me. I re-looked at the 2017 reference I made and thought about the implications. During the last year, I focused my own efforts on an enzymatic solution for the oxidation of nitrogen in L-Arginine by the application of extracted enzymes. The cost of these oxidizing enzymes was however prohibitively expensive and after consulting with Novozymes on the matter, I realised that the direction was unfruitful.

For the first time ever, I personally considered the use of bacteria to deliver the oxidation and found the species of staphylococcus most likely to be involved in the process. The earliest work on the subject I discovered was indeed Morita (1998), but his work was on low-pH salami. Li (2011) seems to be one of the earliest researchers to have noticed the formation and identification of nitrosylmyoglobin by certain Staphylococcus species in raw meat batters and suggested a potential solution for nitrite substitution in meat products. Again, I noticed that in 2017 already, I quoted Møller and Skibsted (2001), who observed that “Parma ham is traditionally produced using only sodium chloride without the addition of nitrate or nitrite and develops a deep red colour, which is stable also on exposure to air. The identity of the pigment of Parma ham has not been established, but bacterial activity has been explored as responsible for transformation into nitrosylated heme pigments.  In one study, the stability of the pigment isolated from two different types of dry-cured ham (made with or without nitrite) was compared to that of the NO derivative of myoglobin formed by bacterial activity. Heme pigment from Parma ham made without nitrite was more stable against oxidation than the pigment from dry-cured ham with added nitrite.” (Møller and Skibsted, 2001)

They observed that “Heme pigments extracted from Parma ham and a bacterial (Staphylococcus xylosus) formed NO-heme derivative had similar spectral characteristics (UV/ vis spectra and ESR). ESR spectroscopy of heme pigment isolated from salami inoculated with bacteria had NO in a predominant pentacoordinate NOheme environment, whereas MbFeIINO, formed from nitrite and ascorbate, exclusively showed hexacoordinated iron, a difference which could be due to the decrease in pH during fermentation.”  (Møller and Skibsted, 2001)

Ras (2017) found evidence for Nitric Oxide Synthase Activity in Staphylococcus xylosus Mediating Nitrosoheme Formation.  

In Europe, Commission Regulation [EU], 2011, The conclusion was drawn that Staphylococcus xylosus has been shown to convert metmyoglobin to nitrosomyoglobin in a culture medium in salami (Morita et al., 1998) and in raw meat batter (Li et al., 2013, 2016), without the addition of nitrate or nitrite.

NO production has been suggested to be linked to NO synthase (NOS) activity. Alderton (2001) also concluded that NOS catalyzes the production of NO from L-arginine and was initially described in mammals (Alderton et al., 2001). 

The all-important question of whether nitric oxide without nitrite will facilitate the inhibition of Clostridium botulinum was answered by Reddy by pointing out that NO₂^– is not the inhibiting factor against c. botulinum, but NO. He writes, “Vegetative cells of Clostridium botulinum were shown to contain iron-sulfur proteins that react with added nitrite to form iron-nitric oxide complexes, with resultant destruction of the iron-sulfur cluster. Inactivation of iron-sulfur enzymes (especially ferredoxin) by binding of nitric oxide would almost certainly inhibit growth, and this is probably the mechanism of botulinal inhibition by nitrite in foods.”

This all places us in a uniquely exciting time, but much work must be done. For example, NO3-, NO2- and NO are like the Christian concept of the Father, the Son and the Holy Spirit in that where you have one, you are likely to find the other. If we then cure meat without nitrites and nitrites develop post-curing, did we solve the matter? The second question is that knowing the facts that I just presented by no means results in a curing system that can be used in a commercial curing operation. What I just gave you have been available in the literature for a decade and a half. It is nothing new to science. Obstacles such as shelf life and colour stability pose daunting challenges, and researchers are working tirelessly to solve the challenges.

In South Africa, the master curer, Richard Bosman, and I partnered to take up the challenge with arguably one of the leading researchers in the world of nitrite curing from an esteemed American University. With partners in Europe, we are starting our own attempt to crack the riddle, and we are energised by existing work that has been done by our European partners. I am myself under restrictions by NDAs in terms of making anything public that is not in the public domain, and both Richard and I will remain bound by relevant agreements and collaborations, yet what has been in the public domain must be noted in a review of curing systems.

Richard and I are very aware that it took two world wars and the efforts of the Griffith Laboratories in Chicago to change the world from NO3- curing to NO2- curing. Only lab work will not spread the gospel, nor will the simple facts that I stated above about the role of microbes in the generation of NO, which cures the meat, lead to a curing system that actually works.

There is an altogether different matter to consider and that is the avalanche of recent work conclusively showing the essential role of nitrite, nitrate and nitric oxide in human physiology. An understanding is emerging that these compounds are not inherently either good or bad for humans or other mammals. In fact, they are essential. Certain conditions, as it were, tip the scale for them to be either destructive or immensely constructive in essentially contributing to our health. Apart from nitrite-free curing, or, I should rather say, parallel to this, we have made it our goal to understand what these factors are and incorporate them into our food systems and we are developing a number of novel ways that we believe it can be done.

Especially related to this section, frustratingly for readers, I do not provide all the references below (work in progress)- I realise this, and as I find time to return to this, I will provide all references and cross-check how I use them. I will confirm that all the references I give are actual work by the quoted scientists, or are they stating facts which they have not verified themselves. I have to ask everybody to forgive me for this approach, as research is not my primary occupation. I actually earn my living through meat processing and do this work in the minutes I am free in the day. As I always do, I will provide the full set of references and verify every comment over time. Accuracy is of the highest importance to me and so if you spot any misquotes, please mail me at ebenvt@gmail.com. There is enough work done, however, on the subject by others to present the general case and explain the direction of our future efforts along with a wide scope of international collaborators.

The N-Nitrosamine Controversy and the discovery of the Physiological importance of Nitrite: Towards Bacon as a Superfood

No survey of meat curing will be complete without a brief mention of the N-Notrosamine issue and the subsequent discovery of the physiological importance of nitric oxide, together with nitrate and nitric oxide to our physiology. In my book on the history of meat curing, which is, in a way, a detailed treatment of this paper, I devoted the closing four chapters to the matter. I refer the reader to them.

These four final chapters form a unit:

• Chapter 16.05: Finally – Nitrosamines
• Chapter 16.06: Finally – Nitrite is Physiologically Vital
• Chapter 16.07: Finally – The Human Nitrogen Cycle – Basis for its Physiological Value
• Chapter 16.08: Finally – Bacon, the Superfood

Finally

This review is done from the perspective of a commercial high-throughput bacon plant. It, however, paints a rich picture and most of what is regarded as “artisan” today has been the way that large throughput factories of yesteryear have done it. In years to come, how bacon was cured even when we embarked on our current bacon project in 2008 will be regarded as “artisan curing” as we have seen the transition to moulds or grid curing over the last 10 years.

I vividly remember my first introduction to the fascinating world of meat curing when I used Prague Powder (invented by Griffiths) and embarked on a quest to find the origins of the name. Over the intervening 24 years, I have been constantly busy trying to understand the curing of meat and I have a sense that we stand at the dawn of significant breakthroughs in terms of our understanding of the natural world and the amazing cycles that govern it. Such a fundamental system is what we see at work in meat curing.

(c) Eben van Tonder

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Reference

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http://www.economist.com/node/8345876

http://www.elmswellhistory.org.uk/arch/firms/baconfactory/baconfactory.html

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Images

Figure 1 and 2: From A Survey of Meat Curing Methods, US Department of Agriculture, Circular no. 894, October 1951, Washington, D. C. 

Figure 3: Founders of bacon plant:  http://www.elmswell-history.org.uk/arch/firms/baconfactory/article2.html

Figure 4:  Stitch pumping, http://www.suffolkheritagedirect.org.uk/resources/tours/made-in-suffolk.html

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Nitrate Salts Epic Journey:  From Turfan in China, through Nepal to North India
By: Eben van Tonder
25 November 2017

Also, see bacon & the Art of Living, Chapter 08.06 – From the Sea to Turpan

Summary

This is the second article in a series that presents a theory that nitrate curing spread from the Tupan/ Turfan region in Western China along the silk and salt trade routes into northern India and Europe.  The first article is Salt – 7000 years of meat-curing. In this article, we expand our knowledge of what was happening in Nepal, North India, Western China and the Turfan area in particular in order to develop a better understanding of the salts that originate from the region.  India once was the major source of saltpeter to the world and I wondered if meat curing did not originate from India.  I start by looking at a very brief history of saltpeter in India pre-colonial and then compare that with saltpeter technology in China and how these validates or contradicts the hypothesis that Turfan is the origin of meat curing.  We identify one more ancient salt that probably predates saltpeter as curing salt of choice, that was mined in the Turfan area.  In our conclusion, we offer a suggestion on how the massive nitrate deposits of this region may have been used alongside this salt in international trade close to the beginning of the Christian era.

Introduction

Where were meat curing discovered?   The easy answer, given at the introduction of many meat science textbooks is that the origins are lost in antiquity.  This will, however, not do.  Despite the fact that it was probably discovered at a time before writing, one can deduce a lot by simply looking carefully at history, even at a time when there were very few or no written records and when preserving meat was not a topic to waste the revolutionary new invention of writing on.  Whether we will exactly discover the answers we are looking for is not as interesting as the quest itself of trying to find it. Like Odesious’ Odessy, in this instance, the journey is the end in itself.

It is remarkable how much one learns by looking into the past.  I became intimately familiar with chemicals which I only knew vaguely and processes that I could not have imagined; I learn about mystical and enigmatic lands and cultures, many of whom endure to this day and I learn to be better at meat curing.

My basic thesis leading to the journey is that nitrate salt’s use in food as preservative originated in the Turpan region in Western China, also called Turfan or Tulufan. According to this hypothesis, it is therefore also the birthplace of meat curing. The article where I first set this out is Salt – 7000 years of meat-curing.  With no understanding of the complex nature of the history of this region and the salts found on its shores, I set out to learn.  I learned that saltpetre was by no means the oldest salt used in meat curing.

Sherlock Holmes said in The Hound of the Baskervilles, “the world is full of obvious things which nobody by any chance ever observes.”  People fail to observe, not because they are lazy or disinterested, but because observing in itself carries risk and is damn hard work. More than that, it is one of the greatest journeys on earth filled with ideas, energy, hope, intrigue, mystery, romance and sometimes even success.

The Land of Aryvarte

A bizarre coming together of random events and the actions of Tristan meant that I would be in the land of the Aryvarte, in the birth land of the Buddha.  Minette, Tristan, Sabin and Duan were set to do the Mardi Himal Base Camp hike as our first introduction to the Himalayas.  What I completely underestimated . . .  well, I underestimated everything, including Nepal itself, its people, its food, its history and its salt!

The country is land-locked between Tibet to the north and northern India to the south. I was definitely in the right region as one of the silk road routes skirts the Turpan region before running south through Tibet and Kathmandu into North India.  Nepal is located in the ancient land called Aryavarta, “or the abode of the Aryana”.  Manu, the ancient law-giver applies the name to the tract of land between the Himalaya and Vindhya ranges; from the eastern to the western seas.”  Later on, the entire region from the Himalayas to Cape Comorin, “and from the Irawady and the Bay of Bengal to the Indus and the Western sea, came to be recognised as Aryvarte.”  (Bhagvat Sinh Jee, H. H., reprint 1998: 13)  I was here.  In this exact place.

The Aryvarte was inhabited by a unique people, the Hindu.  These people, like their neighbours are some of the most impressive on earth.  Their intellectual, cultural and spiritual heritage impressive in every sense of the word.  Their astronomical knowledge date back to 3000 years BCE.  In mathematics, they invented the decimal and the numerical system, geometry and trigonometry.  They had a formal understanding of grammar and philosophy with a well developed legal system.  In terms of architecture, they were unrivaled from the earliest times.  In chemistry, they had considerable knowledge and Bhagvat Sinh Jee credits the Hindu’s of this land with “knowledge of the preparation of sulphuric, nitric and muriatic acids; the oxides of copper iron, led, tin, and zinc; as well as many chlorides, nitrates, sulphates, and carbonates.”  The compendium of knowledge that contains these ancient traditions and teachings is called the Veda (knowledge), from Sanskrit vid, to know.

The Veda, it is believed, is the revealed knowledge of the creator.  They believe that knowledge is acquired and not created, and if this was not so, instruction would be futile.  The discovered knowledge is handed down from father to son and teacher to student.   Four Vedas have been developed.  Rig Veda, Yajur Veda, Sama Veda, and Atharva Veda.  The Brahmans are the custodians of the sacred tradition.  (Bhagvat Sinh Jee, H. H., reprint 1998: 13-19)  The Vedic period spans the mid 2nd to mid 1st millennium BCE with Witzel suggesting the possibility of written Vedic texts towards the end of 1st millennium BCE (Witzel, M) with others opting for a much earlier date.

These dates are important since, in their writing, they speak about various mineral salts, including saltpeter.  My question is how old these references are to try and see how widespread the use and trade in saltpeter was.

The Discovery of a Lifetime

As soon as I gave my first step on Nepali soil, I realised that my entire world and experience as a human were about to change as I entered a land, unlike any I have ever been to.  The beginning of human history is felt in the air.  Unpretentious and honest with no desire to debate any misplaced notions.  Like the Himalayan mountains itself which dwarfs every natural wonder experience without trying to do so; in the same way, the air one breaths fill you with certainty that here a higher wisdom resides which existed from the beginning of time.  Every person is a sage and every human encounter, no matter how mundane, completely educational.

I was unprepared for the trip and yet, in a strange way, life prepared me for months and years for this.  Back in Cape Town, before I boarded the plain, I got myself an ebook version of the 1902 book by Praphulla Chandra Ray, D. Sc., A History of Hindu Chemistry from the earliest time to the middle of the sixteenth century A.D.

A few months ago I became acquainted with the monumental works of the Chinese scholar Needham, Science and Civilisation in China.  I had it on my phone.  Both his 1959 volume 3 subtitled, Mathematics and the Sciences of the Heavens and the Earth and his 1980 volume 5, with the sub-title Chemical and Chemical Technology.  I also recently acquired the landmark work by Berthold Laufer, Sino-Iranica, Chinese Contributions to the History of Civilisation in Ancient Iran, published in 1919.

Before we left Cape Town, I worked a few days 16-hour shifts at Woody’s to put things in place to enable me to leave. Upon my arrival in the classical hotel setting of the in Dalai-la Boutique Hotel, Kathmandu, my body was so used to the 16 hours work shifts that I found myself passing the time from 24:00 to 07:00 when my compatriots started waking, flip-flopping between the works Ray on the chemistry heritage of the Hindu, Needhams almost superhuman thoroughness in tracing the development of the sciences in China and Laufer’s mesmerising and romantic world of Western China, Tibet and Iran.

My subject matter was the salt of the earth, flavours and taste notes.  This deep fusion of spices has only ever been achieved in this region and I believe, the origins of our art of meat curing.  Earlier this year I developed a hunch that meat curing was developed into the universal art it is today beginning in this general region, focussing on the Turpan area in western China.  Being in Nepal put me in the perfect location to develop the thoughts further.

The Problem of Terminology

I was still working on the assumption that saltpeter was the original curing salt and that the ancient history of this salt and meat preservation are the key to understanding the ancient origins of meat curing.  This, I soon discovered, was a wrong assumption, but before I realised this, I ran into a problem with terminology.  What did the ancients call potassium, sodium, magnesium or calcium nitrate salts?

Bhagvat Sinh Jee lists the following principal salts as important in ancient medical traditions from this region.  He made his list in 1896, looking back at the ancient compound chemicals.  He lists Navasadara (chloride of ammonia), Sindhava (chloride of sodium), Pamshujakshara (carbonate of potassium), Yavakshara (carbonate of soda) and Suryakshara (nitrate of potash).  I, however, do not know how old these references are or the exact quotes or reference.  The lists he gives in his work, A short history of Aryan medical science, published in 1896 (Bhagvat Sinh Jee, H. H., reprint 1998: 136) is very interesting.  He mentions nitrate of potash (Suryakshara).  Potash is, of course, the origins of the word “potassium” and nitrate of potassium would be potassium nitrate or saltpeter.  Here I have what I am looking for, but how far do his references go back for the use of the word suyakshara.  I wanted to see how far other authors traced the use of the word back.  What I completely missed, was the first compound mentioned by him namely navasadara or chloride ammonia.  How important this was in the history of meat curing only dawned on me as the time in Nepal went by.

Back to my search for ancient references to saltpetre, Joseph Needham, in his 1980 publication of volume 5 of Science and Civilisation in China, on Chemistry and Chemical Technology quote the Hoovers who wrote that if one looks at the properties of what was called saltpeter in antiquity, it was “mostly soda, more rarely potash, and sometimes both mixed with common salt.”  They stated that if one would try and write a book on all the ancient uses of the word, it would be composed of many volumes and that very early on no single clear definition of saltpeter existed.   (Needham, J.; 1980:  179)

Needham gives a good example of the origins of the word nitre and how this was later confused with saltpetre.  He quotes Jeremiah who wrote:  ‘Though thou wash thee with nitre and soap, yet thine iniquity is marked before me, saith the Lord’ and the Old Testament book of Proverbs which reads, “Confidence in an unfaithful man in time of trouble is like a broken tooth, or a foot out of joint; As one that casteth off garments in winter, or as vinegar upon nitre, So is he that singeth songs to a heavy heart.”

Needham comments, that since the “detergent effervesced with acid, and indeed sodium carbonate it was. This salt occurs naturally, mixed with some bicarbonate, as well as the chloride (2 to 57 %) and the sulphate (1 to 70%), in parts of the Egyptian desert, notably the Wadi Natrun where there is a succession of salt lakes annually inundated, and has been gathered, purified and used for thousands of years.  The proper name for it was natron, a word derived from the ancient Egyptian ntry, hence our modern symbol for sodium; but by assimilation with Gk. nizo and nizomai, to wash, ‘nitre’ resulted, via Gk. nitron and Lat. nitrum. From the IVth Dynasty onwards (c. 2900 BCE) natron was used, never salt, for that desiccation which was the essential process in mummification, being regarded too as a great cleanser, destroying all fat and grease. But it was also used in many industrial arts, such as those of incense, glass-making and the bleaching of cloth.  Nitre continued to have this meaning as late as Agricola, but from the beginning of the + 14th century onwards it was applied also to saltpetre – understandably enough, perhaps, since all these salts were collected from incrustations on the ground. Hence much confusion, even throughout the + 17th century, when saltpetre was often called sal nitri.”  (Needham, J.; 1980:  180)

The ancient use of the word nitre, meaning sodium carbonate or sodium bicarbonate and the confusion that it creates is nowhere clearer than in the reference of Pliny the Elder to the accidental discovery of glassmaking, reportedly 5000 BCE in the north of Israel, south of Lebanon.  The story is not beleived to be historically accurate, but the use of the word nitre is instructive.

“In Syria there is a region known as Phœnice, adjoining to Judæa, and enclosing, between the lower ridges of Mount Carmelus, a marshy district known by the name of Cendebia. In this district, it is supposed, rises the river Belus, which, after a course of five miles, empties itself into the sea near the colony of Ptolemaïs. The tide of this river is sluggish, and the water unwholesome to drink, but held sacred for the observance of certain religious ceremonials. Full of slimy deposits, and very deep, it is only at the reflux of the tide that the river discloses its sands; which, agitated by the waves, separate themselves from their impurities, and so become cleansed. It is generally thought that it is the acridity of the sea-water that has this purgative effect upon the sand, and that without this action no use could be made of it. The shore upon which this sand is gathered is not more than half a mile in extent; and yet, for many ages, this was the only spot that afforded the material for making glass.”  (Natural History)

“The story is, that a ship, laden with nitre, being moored upon this spot, the merchants, while preparing their repast upon the sea-shore, finding no stones at hand for supporting their cauldrons, employed for the purpose some lumps of nitre which they had taken from the vessel. Upon its being subjected to the action of the fire, in combination with the sand of the sea-shore, they beheld transparent streams flowing forth of a liquid hitherto unknown: this, it is said, was the origin of glass.”  (Natural History) When Hippocrates in the fifth century BCE used the Greek word ‘nitron’ and the Latin ‘nitrum’ of Pliny in the first century CE with the English equivalent of ‘nitre’, all these refer to soda obtained from either evaporitic lakes or plant ash (Turner WES, 1956) and not to saltpeter.  The association of nitre with saltpeter only came in the last few hundred years.

Needham’s comment that “all these salts were collected from incrustations on the ground” is key in the consideration of meat curing.  My point is that if these “incrustations on the ground” contained nitrate salts and if these were the salts used from as early on as humans inhabited these regions where natural nitrate deposits are found then the very observant ancient cultures would have noticed it.  This is, in fact, the start of science itself in China, for the Hindu and in the west – natural observations.  What words were used for it and how it was categorised naturally started very broad and uncertain, but I have little doubt that the ancients knew that if salt from encrustations on a particular ground is applied to meat, the meat lasts longer (done in the context of a desert environment where food was scarce and distances challenging to cross even by modern standards); that the meat seems to come back to life by changing to a “living” reddish colour; and, I am equally sure that the distict taste of cured meat did not escape their notice despite the fact that it was the ancient Greeks who first wrote about it.

Ray, dealing with the use of the words for saltpeter in Sanskrit, writes that “the very word [Saltpeter] is conspicuously absent in the literature of the ancients.”  The two words that were used for saltpeter in the Sanskrit languages were sanvarchala and yavakshara, both referring to nitrate of potash.  Later, in Sanskrit, in the Sukraniti and in the Rasarnava, the word translated saltpeter is sauvarchala. He says that it is “very remarkable that in the late Sanskrit chemico-medical literature [this word] ceased altogether to be applied to it (saltpeter)”.  It was later used as a synonym for sarjika (natron).  Instead, the word yavakshara were used, despite the fact that from the time of Charaka and Susruta this word has been used to refer to the ash of barley (impure carbonate of potash; from yava, barley and kshara, ashes).  A number of dictionaries therefore wrongly translate yavakshara as saltpeter. (Ray, P. C., 1902: 99 – 100)  He does not mention Bhagvat Sinh Jee’s suyakshara (potassium nitrate).

Saltpetre works from Ancient North India

The names used for saltpeter was not clear and one had to look at the context of each reference to determine what salt exactly the ancients were talking about.  I was wondered if the saltpeter works in North India held any clue.  Were they trying to refine something they saw from the Turfan area or did the technology of refining saltpeter develop independently from the natural deposits found in West China?

A group was set up by the Middelaldercentret (Medieval Centre), Nykøbing Falster and the University of Leeds namely the “Medieval Gunpowder Research Group” who set out to make and test gunpowder made from ingredients produced as closely as possible using methods of the medieval or early modern periods.  Their reports are fascinating and are all available on the internet.  The following information is from their Medieval Gunpowder Research Group Report6.

They visited north India to get a first-hand account of how saltpeter is collected from the soil.  In their report 6, they deal with possible origins of the nitrate deposits in North India.  From their visit to the region, they report that the “saltpetre soil was collected in the months of March and April. This was somewhat surprising as the sources indicate that it was collected at the end of the rainy season which finishes in September. They further learned that the process of collecting the soil and carrying out the extraction and first, crude, purification was carried out by a group of itinerant workers, from Bihar, who arrived each year in March and April. The area where they collect the saltpetre varies from year to year and we were taken to, and collected samples from, an area that had been exploited in 2004.”

“A possible reason why the soil is collected in March and April may relate to the process by which the saltpetre comes to the surface. From June to September much of India is subjected to the monsoon rains in which the ground becomes highly saturated. The water will penetrate deep into the ground dissolving salts as it does so. When the rains stop the ground starts to dry out and as the water evaporates from the surface, it will draw, by capillary action, the water deep in the soil to the surface, carrying the soluble salts with it. This drying process would seem to take several months with the most salts, including the saltpetre, collecting at the surface when the ground is driest – in March and April – and before the next rainy season. What was also surprising was that no source of potassium, for example, potash, was added during the process but that the end result was potassium nitrate – one would expect calcium salts to predominate.”

Why is this such an important question?  It has been known since the groundbreaking work of  Müntz and Schlössing in 1877 that bacteria are responsible for the oxidation of ammonia and amonium to nitrite and nitrite to nitrate.  Sergei Winogradsky (1856 – 1953) became the first person early in 1890 to isolate bacteria that reduce  (ammonia) to   (nitrite) (Nitrosomonas and Nitrosocococcus) and found that bacteria of the genus Nitrobacter oxidizes nitrite to nitrate.  This formidable scientist showed that these organisms use the energy released from nitrification to drive their metabolisms.  (Lodders, K. and Fegley, B. Jr.; 2011: 376)  When organic matter is broken down during decomposition by these microbes, predominantly calcium and magnesium nitrates are produced as waste product.  This means that saltpeter from such decomposition starts life as either calcium or magnesium nitrate.

Saltpeter is then created from these.  The first printed work in the West on metallurgy, De la pirotechnia, written by the Italian Vannoccio Biringuccio and published in Venice, sets these steps as mixing the nitrate salts in water with quick-lime and wood ash.  The nitrates react with the potash ( forms from the wood ash) in an alkaline solution to form two highly insoluble salts, calcium carbonate (limestone:  ) and magnesium carbonate (mahnesite:  ).  This leaves saltpeter or potassium nitrate  in solution.

This question of the origin of the potassium in the North Indian saltpeter “was discussed with Professor Rajiv Singha of IIT-Kanpur who believes that the answer may be that the area is fed by rivers that run through areas rich in potassium salts. But this does not answer the question of where the nitrate comes from. It is not a naturally occurring salt and is produced by the reaction of bacteria with area and ammonia compounds in animal waste, particularly urine. Was the source of the nitrate here also from this process or were there other factors at work? A possible explanation is that the very high population, of both people and animals, has over a very long period, possibly millennia, produced a high level of nitrate in the soil and this is still coming to the surface.”

The process of collecting and refining saltpeter in this region is ancient.  The question now comes up what the ancients called the saltpeter soil.  Ray writes that “it is strange indeed that a substance which occurs exclusively in Bengal and in upper India as an efflorescence on the soil should have been allowed to go without a definite name for several centuries.”  He then quotes Dutt who said that “nitre was unknown to the ancient Hindus.  There is no recognised name for it in Sanskrit.”  (Ray, P. C., 1902: 100)  He continues that in his time there were “some recent Sanskrit formulas for the preparation of mineral acids containing nitre” where this salt is referred by the name soraka.  “This word, however, is not met with in any Sanskrit dictionary and is evidently Sanskritized from the vernacular sora, a term of foreign origin.”  (Ray, P. C., 1902: 99 – 100)

I speculate that they used the salt in an unrefined form for millennia for various industrial and medical uses.  I have not reviewed the climate history of the region but the current climate lacks the incentive for the development of meat curing which suits desert conditions better where hunters,  nomads, and traders had to travel vast distances without any hope of finding food.  I would speculate that preservation was probably the first incentive for using these salts with the ability to change the meat colour back to a healthy reddish colour as a secondary importance.  This again points to the Turpan area as the birthplace of meat curing and not North India where the development of saltpeter technology was later than in China.

Ray makes the same point when he says that “the manufacture of nitre was, therefore, most probably introduced into India after the adoption of gunpowder as an implement of war.”  (Ray, P. C., 1902: 99 – 100)  I am interested to know when this was and decided to review the chronology.  According to Frey, the watershed time for India between the age of the blade and the age of the gun came in the early sixteenth century.

He states that “it is likely that Mongols who introduced the making of fireworks to India in the mid-thirteenth century. We know almost nothing about saltpeter production during this early period, but technical expertise apparently diffused with the adoption of rocketry and eventually artillery by Indian rulers in the fourteenth century. The break-up of the Delhi Sultanate, the rise of regional states, and the growing presence of Turkish mercenaries in India may be linked to the establishment of regular saltpeter production and the adoption and use of gunpowder weapons.”  (Frey, J. W.; 2009: 512)

“By the fifteenth century, Indian rulers began to acquire significant parks of artillery, and direct references to saltpeter production suddenly surface, especially in Bengal and neighboring Jaunpur, sultanates dominated at the time by Afghan warlords. Two Persian dictionaries of the period, written by court scholars from these regional states, describe saltpeter manufacturing in detail. These references are telling because the area lying between Jaunpur and Bengal eventually emerged as the premiere saltpeter-producing region of India. As early as the 1460s, nearly forty years before the commencement of the East India trade, these Persian sources make it clear that the rulers of Jaunpur and Bengal already had organized production as state monopolies managed by their chief merchants.  (Frey, J. W.; 2009: 512, 513)

Abu’l-Fath Jalal-ud-din Muhammad Akbar, known as Akbar I and later as Akbar the Great, became the third Mughal emperor, who reigned from 1556 to 1605. His land included what is today known as north India.  He made effective use of gunpowder which by the mid 16th century became widely available.  Fey writes “we do not know precisely how Akbar’s army acquired gunpowder, but the importance of saltpeter was understood by the Mughals, who demonstrated an interest in the technical aspects of its production and use. Significantly, the saltpeter grounds of Bihar are not mentioned by Abu al-Fazal, although they certainly existed in Akbar’s time. The general impression given by the A’in-i Akbari is that possession of firearms and powder manufacturing were decentralized, at least in Akbar’s empire.” (Frey, J. W.; 2009: 517)

Sher Shah Suri (1486–1545), the founder of the Sur Empire in North India, with its capital at Delhi ruled the empire from 1540 to 16545 over which Akbar ruled and made widespread use of gunpowder.  In a way, Akbar only followed in his footsteps and progressed technology and tactics that was introduced by Sher Shah Suri in the 5 short years of his rule.  Interestingly enough, it was a gunpowder explosion that ended Suri’s life in 1545.  During his time the state was even less involved in gunpowder production and he ordered local officials to “purchase from local bazaars at current prices.” (Frey, J. W.; 2009: 517)

This is a statement that fascinates.  “Purchase from local bazaars at current prices“.  We have the “adoption of rocketry and eventually artillery by Indian rulers” associated with the establishment of regular saltpeter production and the adoption and use of gunpowder weapons in the fourteenth century.  By 1540, gunpowder, and presumably saltpeter was so common in north India that officials were ordered to purchase it from local bazaars, al current prices. The transition years, therefore, as far as north India is concerned seems to be the 250 years between 1300 and 1540.

Why is this important?  Lets for a moment forget about the question if meat preservation was necessary for north India.  If saltpeter was the curing agent of choice in any area, it had to be available and if curing spread from this region, surely the salt used in curing had to be traded under a specific name.  The military demand undoubtedly increased saltpeters general availability even though, at times of war, it would certainly also have restricted its availability as it did during the First World War which resulted in the change from saltpeter to sodium nitrite in meat curing.  This, however, only happened in India between the years 1300 and 1540.

Gunpowder came from China

Gunpowder was invented in China.  “The oldest mentions of gunpowder in Europe are all unquestionably of the late + 13th century, preceding its general introduction in the + 14th. In China, on the other hand, we have the first reference to the gunpowder mixture in the + 8th or + 9th century, its appearance in war early in the + l0th, and its widespread military use in the + 11th and + 12th before it reached Islam and Europe in the + 13th.” (Needham, J.. 1980:  195) The oldest reference to a proto gunpowder mixture comes to us from c. 850 in the Chen Yuan Miao Tao Yao Lueh where there is a test for saltpetre. (Needham, J.. 1980:  187)  This means that saltpeter related technology was already mentioned in China, 450 years before it developed in India.  This, in turn, seems to support the notion that meat curing developed in regions closer to China or in China itself.

A side comment is in order here.  Reviewing the evidence from China makes it clear that Chinese alchemists of the 8th and 9th century were able to distinguish between potassium nitrate and other alkali metals for the purpose of gunpowder production.  My question is if the average salt trader or the general public had this ability which they most certainly did not possess.  This means that an exact and accurate description of every salt sold in the markets and pharmacies of the day was a dubious affair at best.

Up to this point, we have seen that the world leader in saltpeter related technology was China with records dating back to 850 BCE.  Despite ancient references to it in Hindu literature and the fact that it occurs in North India, the identification, analysis, and application of technology related to nitrate salts were first done in China and not India.  Or so it would seem.  There is an interesting story that Needham recount which may show that mineral acids, such as nitric acid were known in both India and in China by the 7th century.  We will return to this in a subsequent article.  Needham tells it in section (3) Saltpetre and copperas as limiting factors in east and west. (Needham, J.. 1980:  195)  Still, it would seem that the clear mention to saltpeter in China, predates any other.

Tracing References to Saltpeter in Chinese Records

Needham writes that “the ‘nitre’ complex, too, is simply one typical example of the difficulty of identifying the substances used by the medieval alchemists and pharmacists. The most helpful signs to go by are always the descriptions of the properties of the substance concerned mentioned in any given Chinese text. Thus of hsiao shih (which goes back as a name to the – 4th century) it is often later said that it gives a bluish-purple flame when put in the fire, a statement which immediately rules out salts of sodium and magnesium.” (Needham, J.. 1980:  193, 194)

“The oldest description of this test comes from about + 500, but it could safely be placed a couple of centuries earlier, as far back as Ko Hung. Many alchemical and pharmaceutical texts from the – 2nd century onwards also say that hsiao shik can liquefy ores, acting as a fluxt and dissolve minerals to form aqueous solutions.  There are also instances where hsiao shik is said to produce explosions or deflagrations, and we have of course the gunpowder formulae with hsiao shih in them. In such circumstances one can feel fully justified in extrapolating back the results of analyses ·of modern samples of hsiaosmh which show it to be saltpetre.”  (Needham, J.. 1980:  193, 194)

Rightly therefore was it called in Arabic, Chinese snow, for it was recognised and used in China long before anywhereelse. The oldest extant Arabic mention is in the Kitiib al-Jiimi’ fi al-Adwiya al-M.ufrilda (Book of the Assembly of Medical Simples) finished by Abti Muhammad al-Mllaqi Ibn al-Baitarg about + 1240. Others follow shortly after.  (Needham, J.. 1980:  193, 194)

A Fascinating 1871/ 1872 Mention of Meat Curing with Salts from Turpan

This being the case, what preceded the use of saltpeter as curing salt?  In a region where nitrate salts naturally occur, it is easy to see that it was used for preserving meat.  It would be a mixture of various salts among whom there would have been nitrate salts.  We are however not investigating a claim that it was used as curing agent locally in the Tarim region, but if this was where curing developed in a way which spread across the world.  For this to be the case, the salt in question must have had a particular name and there must be references that it was traded.

We can ask the question like this:  Was it a “luck of the draw” if salt bought at the market may or may not have contained nitrates or could the client ask for a particular salt.  If saltpeter’s use only gained momentum parallel to its inclusion in the production of gunpowder, was there another salt from ancient times or another name for salts used that could cure meat?  One would expect such a salt to have a specific name and evidence of it being traded.

An ebook from 1871/1872, Pharmaceutical Journal: A Weekly Record of Pharmacy and Allied Sciences, Volume II, published by J and A Churchill from London yielded an unexpected nugget. It quotes another work entitled Contribution towards the material medica and natural history of China, for the use of medical missionaries and native medical students.  The author is Frederick  Porter Smith who refers to himself as a medical missionary to central China.  He writes that the work is the result of two years of leisure spent in the city of Hankow.  He listed different substances found in the drug shops of the Chinese and in dispensaries attached to the mission hospitals.  He lists the product and gives a short history and use of each article.

The substance listed as an example of his work is on Sal Ammoniac.  At first, I am disappointed that they don’t list saltpeter, but as I look deeper into this salt of Ammon, I realise that I have just found the kind of alternative curing salt I was looking for whose popularity predates saltpeter.  My focus on saltpeter was valuable to bring curing in the 1700’s and 1800’s in Europe into perspective, but this was by no means the only salt known from antiquity that contained nitrogen.  Nor was it the most well known.

I realise that in the many works on saltpeter which are almost exclusively dedicated to the development of gunpowder, of course, the focus must be on the nitrate salts.  Here you need the three oxygen atoms to provide the explosive power which is found only in nitrate.  Nitrate is valuable in meat curing not in and of itself, but in that it is changed into nitrite when it loses one oxygen atom through bacterial action.  Nitrite is the starting point of chemical reaction sequences which end up in nitric oxide formation which cures the meat.  This is true but what I failed to seriously consider is that ammonium is also changed into nitrite through bacterial metabolism, just like nitrate.  In the case of ammonium, two oxygen atoms are added to form nitrite.

The reason why I never seriously considered it was that I failed to appreciate the universal occurrence of sal ammoniac and thought it was restricted to regions in Egypt.  Nor did I have any inkling of the massive trade that was done in this salt.

Let’s get back to Smith’s work and I quote the example he gives namely his entry on Sal Ammoniac.  He writes, “Nau-sha, Nung-sha, Peh-ting-sha – this saline substance, the chloride of ammonium of chemists, is brought from Lan-chau-fu and Ning-hia in Kan-suh.  The country of the Tih, or Si-jung and Turfan formerly yielded it.  The volcanic mountain of Peh-ting in Turfan is said to have yielded some ammoniacal salt from fissures in its sides, and hence the name Peh-ting-sha, more correctly given to volcanic ammonia.  The Chinese name Nau-sha is very like the Hindustani name Naushadar or Nausadar, given to thick, fibrous translucent cakes of the crude salt of ammonia obtained in India from the unburnt extremity of brick-kilns in which the manure of camels etc. is used as fuel.  (Dr. Waring’s Ph. of India, p. 309)  Keferstein affirms that both carbonate and muriate of ammonia are found in China, but the dirty-white, rough, deliquescent salt commonly sold under this name is nothing but sulphate of soda or common salt.  Nitro (soda-nitrate) and borax are also confounded with it.  It is used as a flux or solder, or is said to be so employed.  Whilst the salt is said to be deleterious, it is also said to be used in curing meat, or as a condiment.  It is mainly used as a solvent for opacities of the cornea, for which the sulphate of soda acts almost as well.  It acts as a sedative, resolvent, deobstruent, pectoral and mild escharotie, in Chinese estimation.  They use it in veterinary practice.  Some of the samples contain iron and resemble the Kala Nimuk of India. ”

So, from the same region we now know that not only is it replete with nitrate salts, but due to volcanic activity, the famous salt from Egypt, sal ammoniac is found.  I have little doubt that the information about the Smith’s reference of the “volcanic mountain of Peh-ting in Turfan is said to have yielded some ammoniacal salt from fissures in its sides” comes from the work of none other than Alexander von Humboldt (1850; Views of Nature).  He almost quotes Humboldt verbatim.  As Smith states, this was a time when different salts were easily confused and the mention of meat curing with sal ammoniac is of particular interest.

It occurred to me that Sal ammonia may have been the forerunner of saltpeter as the curing agent of choice.  It is composed of two ions, ammonium, and chloride.  The ammonium would be oxidized by ammonia oxidizing bacteria (AOB) into nitrites and the well-known reaction sequence would result.  Reaction Sequence

Not only would it result in the reddish-pinkish cured colour, but it was an excellent preservative.  An 1833 book on French cooking, The Cook and Housewife’s Manual by Christian Isobel Johnstone states that “crude sal ammonia is an article of which a little goes far in preserving meat, without making it salt.”  (Johnstone, C. I.; 1833: 412)  It is, of course, the sodium which tastes salty in sodium chloride and ammonium chloride will have an astringent, salty taste.  I know exactly what ammonium chloride taste like since it was added to my favourite Dutch candy “Zoute Drop” with licorice.  I believe it was none other than my old friend, Jan Bernardo who first gave me Zoute Drop.  As a boy, I used to ride my bicycle once a month to the only Greek Caffe in Vanderbijlpark which sold it for my monthly fix.  My favourite was the double strength version called “Dubbel Zoute Drop.”

Smith states that mistaken identifications were commonplace.  He said that “nitro (soda-nitrate) and borax are also confounded with it.”  Nitro is, of course, the salt that we are more familiar with for meat curing and this region contains one of the largest natural nitrate deposits on earth.

The fact that sal ammoniac was confused with sodium nitrate is interesting.  In order to evaluate this statement, we have to understand how the massive nitrate deposits in this region came about.  Atmospheric nitrate finds its way to earth through a process which we call the nitrogen cycle and is the main way the earth fertilises itself.  It almost never “accumulates” in vast reservoirs, especially not in the open land due to its high solubility.  Water dissolves it and carries it into the soil where plants use it as fertiliser and bacteria use it in their metabolism, producing a new compound with a different oxidation state.

It is known to accumulate in a few regions on earth.  Two factors are responsible for this namely age and the dryness of the region.   The Turpan-Hami area is one of driest regions on earth with average annual rainfall of 15mm and “intense evaporation often times 200 times the rate of rainfall.”  On top of this, there is little surface vegetation which would, of course, use the nitrates as nutrition coupled with the occurrence of strong north-west winds which would dispell any surface precipitation. (Yan Qin, et al, 2012)  The result in regions like this is atmospheric nitrogen build-up in the form of nitrates.

Nitrate deposits are widely distributed in the area (Yan Qin, et al, 2012) and the amount of nitrate in the Turpan-Hami basin is estimated at 250 million metric tones which rival those of the famous Atacama nitrate deposits (Wensheng, G. E., et al, 2014).  The most common nitrate deposits are found in the top 50cm of the surface layer towards the center of the basins, particularly in the Turpan basin (this is in contrast to the Atacama deposits which occurs deeper down).  Its origin has conclusively been demonstrated to be from the atmosphere.  (Yan Qin, et al, 2012)

The soil, however, never contains only nitrate.  It is a rich mixture of different minerals and in the Turpan-Hami basin, it is particularly interesting since it is naturally engineered to contain not only nitrates but a rich mixture of minerals ideally suited for meat preservation.  The soil is a mixture of nitratine, the natural form of sodium nitrate; halite, which is the mineral name for salt or sodium chloride, or rock salt; and mirabilite or Glauber’s salt which is a hydrated form of sodium sulfate.  The nitrate composition ranges from between 2% and 27.98% of the ore tested and average at 10% in the 2012 study by Wensheng, G. E. and coworkers. Halite or sodium chloride was at an average of 30%, darapskite, a crystalized rare mineral which is chemically  a water-containing sodium nitrate sulfate, at 20%, nitratite or sodium nitrate at 10%, and thenardite, an anhydrous sodium sulfate mineral (Na₂SO_4), anhydrite, an anhydrous calcium sulfate mineral, CaSO₄, bassanite, a calcium sulfate mineral with formula CaSO₄·0.5(H₂O) or 2CaSO₄·H₂O, and glauberite, a monoclinic sodium calcium sulfate mineral with the formula Na₂Ca(SO₄)_2, at an average of 3 -8%.  (Wensheng, G. E., et al, 2014).  From these, it is easy to see how, if the rocks containing these minerals were crushed and applied to meat, it acts as a powerful preservative due to the presence of the three key elements used in food preservation to this day namely nitrate, sulphate and chloride.

But what about Smith’s sal ammoniac which was confused with nitro (soda-nitrate).  It is unlikely that the sal ammoniac mined from the fissures from the sides of the volcanic mountain of Peh-ting in Turfan was mixed with the massive nitrate deposits of the region.   Yan Qin, et al (2012) reports that “significant nitrate deposits are only found at least ~15 km away from foothills” which rules out accidental contamination when the sal ammoniac was mined.  The answer shows that pure sal ammoniac had nothing to do with the massive nitrate deposits and introduces us to another one of the many ammonia salts.  Of course, sal ammoniac almost never riched its destination in Eastern China and Europe as a crystal, but due to moisture, as looking similar to other incrustations on the ground. 

Sal Ammoniac

Lets look a bit closer at the characteristic of sal ammoniac.  Several minerals exist composed of ammonium (NH₄). Ammonium is formed by the protonation of ammonia (NH₃) . Sal Ammoniac is the most well known and was named by the ancient Romans.  They collected this salt which was found around the temple of Jupiter Ammon in Egypt and called it salt (sal) of Ammon (ammonocius).  The name ammonia was subsequently derived from it.  It forms in volcanic vents and after volcanic eruptions before it has rained which dissolves it.  It is highly soluble.  It is unique in that the crystals are formed directly from the gas fumes and bypass the liquid phase, a process known as sublimation.

Ammonium readily combines with an acid thus forming a salt such as hydrochloric acid to form ammonium chloride (sal-ammoniac) and with nitric acid to form ammonium nitrate.  Recent studies have shown that volcanos release a “previously unconsidered flux of nitric acid vapour to the atmosphere.  (Mather, T. A., et al, 2004) Of course, whether this is the nitro that Smith refers to is only speculation, but what is a fact is that the Turfan area, both the basin and the mountains is replete with different salts containing nitrogen (nitrate salts and ammonium) any one of which could be used effectively in meat curing.

Trading Sal Ammoniac

The one key component was still missing namely evidence of a large-scale and “universal” trade in this salt, possibly even on a scale that set it apart from saltpeter or any other salt.

An unexpected surprise emerged from the work of Valerie Hansen and the area where the records were compiled is none other than from ancient Turfan itself.  Turfan (Turpan) is located on the northern route around the Taklimakan desert and forms a bridge between the Chinese and Iranian worlds.  Valerie Hansen, in her brilliant work on the silk road (The Silk Road: A New History), describes the current day cosmopolitan feel which the city probably always had.  “Vendors on every corner sells naan, the leavened flatbread like that is eaten in central Asia and North India. At a conference, I attended there in the mid-1990’s, a Norwegian professor of Iranian languages cheerfully greeted everyone at breakfast, explaining that it was the first time he had woken up to the sound of braying donkeys since being in Iran before the 1979 revolution.  In town, one sees many Uighur and Chinese faces, and the proprietors at the bazaar – even Chinese speakers say “baza’er” and not the Chinese word for “market” – proffer rugs, glistening jeweled knives, and always a glass of tea to potential customers.” (Hansen, V.;  2012)

Historically Turfan comprised of mainly two peoples, Chinese and Sogdiana, from the region around Samarkand, the oldest inhabited city on earth dating back to the 8th or 7th century BCE, located on the Silk Road and linking China and the Mediterranean.  The Han dynasty fell in 220 AD and large numbers of Chinese migrated to the northwest.  Turfan and Kucha were the largest two settlements on the northern route around the Taklimakan.  The Sogdians felt that Turfan was so Chinese that they referred to it as Chinatown.

There was a practice in Turfan that unwittingly gave us a remarkable record of their society.  They recycled paper that was written on by using it to make shoes, belts, hats, and clothing for the dead.  The source material is therefore random and unedited by someone who wants to bring his or her own particular message across.   Chinese in other regions had the same practice, but it was here in Turfan where conditions were best for preservation due to the low humidity.  The lowest region in Turfan is 154m below sea level, the second lowest point on earth, after the Dead Sea.  Turfan is dry and hot and the Chinese referred to it as the prefecture of fire.  Summer temperatures reach 60 deg C.  (Hansen, V.;  2012)

The southern silk route fell into disuse in 500 AD and many travelers opted for the northern route through Turfan.  By 640 AD, a census listed the number of people living in Turfan as 37 700 and 8000 households.  Hundred years later, the number of households increased to 11 647.  The city was one of significance and documents from the gravesites in the area offers a unique insight into life on the silk road.  (Hansen, V.;  2012)

The first fragment of interest in our quest shows the close contact between the people from the region.  This fragment from 477 lists expenses for hosting envoys from “the Rouran people of central Asia (known in Europe as the Avars, a nomadic people), the Karghalik kingdom on the southern edge of the Tarim basin; the Song dynasty (420 – 479) whose capital was in Nanjing, China; the Uddyana kingdom in north India, and the “Brahman country,” most likely a reference to South India.”   This shows us some of the neighbours that Turfan maintained diplomatic relations, but trading extended to others also.  Coins and documents show trading relations with Iran, especially the eastern Iranian world of Samarkand which was their most important trading partner of the first independent Goachang Kingdom and not Rome, as one may expect. (Hansen, V.;  2012) This city will become very important in our discussion on sal ammoniac.  Later, after 640, the most important trading partner was Tang China. (Hansen, V.;  2012)

Many of the Sogdians lived in Turfan.  Around 600 AD, Gaochang officials recorded the names of 48 merchants who paid tax on goods they sold to each other.  These documents survived in 10 paper shoe soles cut from four sections of the register, recorded over a year.  This is the single most important document offering us information on the commodities traded on the silk road.  (Hansen, V.;  2012)

The first valuable bit of information is not the commodities itself, but the importance that Sogdians played in the Silk Road trading.  Of the 48 names listed, either as buyer or seller, 41 are Sogdian. A total of 37 transactions are listed over the course of a year comprising of brass, medicine, copper, turmeric, and raw sugar, being traded only once in that year.  The more frequently traded commodities were gold, silver, silk thread, aromatics (the term xing refers broadly to spices, incense, or medicine) and ammonium chloride.  (Hansen, V.;  2012)  Valerie Hansen elaborates on the last commodity of ammonium chloride and states that it was used as an ingredient in dyes, to work leather, and as a flux to lower the temperature of metals.  Ammonium Chloride is listed six times in these documents.

Joseph Needham summarised many of what we discovered about sal ammoniac in the 3rd volume of his monumental work, Science and Civilisation in China.

He gives context for the terms used for sal ammoniac in Chinese and its possible origin.  What is of supreme interest is the fact that it was agreed on by all Chinese books that this salt came from the Western regions, including Tibet and Turfan.

He writes about the uses and origin of the salt that it “was important both medically (a stimulating expectorant or couch medicine and mild cholagogue) and chemically.  Its medical use as a cough medicine continued long into the 1800’s in Europe.  “Stapleton thought that it was probably introduced into chemistry by the Arabic alchemists towards the end of the 10th century, partly because they were able to prepare it by the dry distillation of hair,”  a view that I still find to be widely held today.  Needham continues that it nevertheless “occurs naturally in volcanic situations in Central Asia and was probably collected from there from an early date.” (Needham, J.; 1959:  654, 655)

“Stapleton suggested that the Arabic word mushadur was perhaps derived from the Chinese nao sha a suggestion which Laufer somewhat cavalierly dismissed.  Laufer’s view that the borrowing was in the inverse direction was so far plausible in that no one (including Chang Hung-Chao subsequently) had been able to find any reference to nao sha in Chinese texts earlier than the 6th century AD, when the Wei Shu was written (572 AD).  It had not been noticed that it occurs in Wei Po-Yang’s 2nd century AD Tshang Thung Chii where it bears a correct reference to the refrigeration effect of the salt on boils.  Whether Ko Hung’s lu yen means sal ammoniac is not clear, and the next main reference in a technical book is apparently the Thang Pen Tshao of 660 AD.  Now, it is indeed remarkable, as Laufer pointed out, that the orthography of the Chinese term is so fluctuating, a fact which would suggest a phonetic transcription.  In works of the 7th century AD, such as the Sui Shu, variants such as noa, nung, and jao (all probably homophones of nao) are found.  In the 9th century AD Mei Piao writes miu (probably also then pronounced nao).  In the 6th century AD, Wei Shou (in the Wei Shu) had written kang or wang.  This word persists through Thang and Sung books, and nao seems to have become definitely stabilised in the Ming.”  (Needham, J.; 1959:  654, 655)

Apart from the information on the different words and a possible connection between them, we can say that the earliest reference to this salt from Chinese records is from the 2nd century AD.  Contrast this with saltpeter that, in a more refined state, became common in India around the year 1300 and was found in markets with gunpowder at the beginning of mid-1500’s.  In terms of what we can learn from written history, it pre-dates references to saltpeter in India by at least 1000 years.

“All the Chinese books agree (for example the Hsi Yü Thu Chi) of Phei Chü, c 610 AD; the Pên Tshao Thu of Sung Sung, c 1070 AD, and the Yeh Huo Pien of Shen Tê-Fu, c 1398) that native sal ammoniac came from the west, i.e. Szechuan, Kansu, Sinkiang, and Tibet where it was collected from the neighborhood of volcanic fumaroles.Towards the end of the 18th century, the Manchu geographer Chhi-shih-i Lao-jen said in his Hsi Yü Wên Chien Lu (Things Seen and Heard in the West Countries) concerning Kucha and Turfan: “Nao Sha is produced in the mountains of that name which are north of the city of Kucha.  In spring, summer, and autumn, the caves there are full of fire.  From a distance, they look like thousands of lamps, and approach is difficult because of the heat.  In winter, due to the excessive cold and heavy snow, the fires die down.  Local people go there to collect the sal ammoniac, entering the caves naked because of the heat.””  (Needham, J.; 1959:  655)                             

“In his Chu Yeh Thing Tsa Chi (Miscellaneous Records of the Bamboo Leaf Pavillion) a century earlier, Yao Yuan-Chin wrote: The mountains where sal ammoniac is produced near Kucha were called in the Thang the ‘Great Magpie Mountains’.  No one dares go near them in the spring or summer.  Even in the cold weather, the people take off their ordinary cloths and wear leather bags with holes through which they can see.  They enter the caves to dig up (the sal ammoniac), but come out after one or two hours and could not possibly stay longer than three; even them the leather bag is scorching hot.  The nao sha sparkles on the ground, but not much of it can be obtained.  The product has to be kept in earthen jars with their mouths tightly closed and kept cool, otherwise it will disappear.  It will also disappear if subjected to wind, wetness or damp; leaving only a white residue of granular appearance.  Though this is the least valuable part, it is probably the only kind which finds its way to the central parts of China.” (Needham, J.; 1959:  655)

“These descriptions have close parallels to Arabic authors.  On account of this volatility, so well recognised,  ammonium chloride acquired another Chinese name chhi cha; and doubtless, because of its western origin, it was also known as ti yen barbarian salt. It was probably always impure, often mixed with sulphur and sulphites [and, may I add, nitrates].  If, as seems likely, its collection in volcanic Central Asian regions goes back very far, the earliest term may well have been Sogdian or Persian giving rise later both to mushadur and to nao sha.”  (Needham, J.; 1959:  655)                            

The fact that sal ammoniac arrived at its destinations as “a white residue of granular appearance,” mined from the exact place that holds the largest sodium nitrate deposits and the many similarities between sal ammoniac and saltpetre; that these salts were often confused, leaves me with little doubt that even though trading records identify the salts as sal ammoniac, often, it quite possibly was salt taken from the centre of the Tarim basin containing nitrate and sold as sal ammoniac.

The mining of sal ammoniac at Turfan has been reported on in Western media as recently as 1821.  An article appeared in the Gettysburg Compiler on 20 June 1821 where a Chinese encyclopedia was quoted which said that two active volcanos exist “in the interior of Tartary from which sal ammoniac is obtained by the Tartars and distributed in the way of commerce.  There are cavities in these volcanos, in which greenish liquid collects, which, when exposed to the air, changes into a salt.  One of these mountains is called Tourfan or the Hill of Fire and the other, Ho-Hebcon, or the town of fire.  A column of smoke continually rises from the former, which, in the night becomes a flame similar to that of a flambeau.  Birds and other animals illuminated by it appear of a red colour.  Sabots, or wooden shoes, are worn by those who collect the salt, for leather shoes would soon be burnt.”  (Gettysburg Compiler, 1821, p 4)

An interesting bit of new information is added namely that “the people of the neighborhood also collect the mother waters, which they boil in vessels, and obtain the sal ammoniac in lumps or loaves, like those of common salt.”  (Gettysburg Compiler, 1821, p 4)

Sal Ammoniac and meat curing:  Evidence from Modern Literature

Despite my notions about the deliberate confusion of sal ammoniac and nitrate salts, let’s ask the question if there are any modern evidence of the use of sal ammoniac in meat curing.

Here are a few references that an internet search yielded.  There is the 1833 reference from Isobel Johnstone that we already referenced that “crude sal ammonia is an article of which a little goes far in preserving meat, without making it salt.”  (Johnstone, C. I.; 1833: 412)

The 1842 edition of The Encyclopaedia Britannica reports the results of Sir John Pringle who did experiments to determine the powers of certain substances to prevent putrification in the context of meat preservation.  He lists sal ammoniac as number 7 on his list with an assigned value of 3.  Nitre is listed as number 9 with an assigned value of 4+.  Sea salt or standard salt is listed first with a value of 1.

An 1868 publication, On Food, says that “saline substances such as saltpeter, acetate of ammonia, sulfite of potash, or soda,  muriate of ammonia (sal ammoniac or ammonium chloride) etc, are also good presetvative agents” for meat.  They are brushed onto the surface of the meat or injected.  He makes mention of several patents pending for injection of preservatives into fresh meat by Long (1834), Horsley (1847), Murdock (1851) and others.  (Letheby, H., 1870)

The very clear statement of Smith 1871/72, made from within China, in reference to how it is used in China itself serves as our strongest point of reference.  Let’s repeat his statement again.  “[Sal ammoniac] is said to be used in curing meat, or as a condiment.”

Hiscox lists it in 1916 along with saltpeter as a preservative in Rubrolin Sausage (spice powder).  For every 100 parts by weight, take 53.5 parts by weight sal ammoniac and 42.5 parts by weight of saltpeter.

On 13 March 1989, an application is filed by Herbert F. Angermeier from Liberty Provisions Inc. from Clifton, New York, for a patent registration for a curing process for meats which comprises of ammonium chloride, ammonium phosphates, and potassium phosphates.  The object of the cure is to provide a sodium free meat cure, but the fact that sal ammoniac is fascinating. (US4894249 A)

A surprising, but completely logical use of ammonium chloride emerges.  I was intrigued by the timing of when sal ammoniac is added from a recipe in the Tradesman of 1809.  It reports on an English method for curing ham, tongue, etc.   A certain Frederick writes to the magazine offering some recipes for curing meat.  He is a man with 18 years of meat curing experience who has done extensive experiments of finding cures that will last on long sea voyages and he is the owner of a commercial curing operation.  He applies his recipe to pork, mutton hams, hung-beef, tongues, etc.

A cure mix is prepared with the usual amount of salt, but double the saltpeter.  Salt the hams for a week and stack them on top of each other, every day, as was the custom.  In the process, meat juices will be drawn from meat.  For argument’s sake, take the juices thus drawn from 24 hams.  Mix in the juices, 1/4 pound of fine sal ammoniac, 1 pound of Muscovado sugar.  Mix it with a stick and pour it over the meat, turning it every second day for 14 days.  Dry them for a week.  Then smoke them using oak sawdust mixed with Juniper Berries.  Smoke for another 8 days.

His total curing time is 3 week, 1-week drying and a further 1-week smoking.  Total processing time of 5 weeks.  The question plagued me.  Why would Frederick, the astute curing artisan and business owner that he was, have added the sal ammoniac a week after the saltpeter was added when both needed bacterial action of oxidation and reduction, respectively which are both time-dependent processes.

An 1880 publication of a Farmers Guide, published by S. Anderson, Jr. from
Linwood, Delaware Co., Penn, gives the following freezing preparation.  “Common sal-ammoniac well pulverized, one part, saltpetre, two parts; mix well together; then take common soda, well pulverized. To use, take equal quantities of the preparations (which must be kept separate and well covered previous to using) then put them in a freezing pot; add of water a proper quantity, and put in the article to be frozen in a proper vessel covered up, and your wants will soon be supplied. For freezing cream or wines this cannot be beaten.”

When an ionic salt dissolves in water, the reaction is endothermic meaning that heat is absorbed from the environment by the reacting chemicals.  In order to compare the difference between different salts familiar to us, let’s look at the following.

1 mole of sodium chloride (normal table salt) crystals are dissolved in an excess of water, the enthalpy change of solution is found to be +3.9 kJ mol^–1

1 mole of ammonium chloride (sal ammoniac) crystals are dissolved in an excess of water, the enthalpy change of solution is found to be +14.7 kJ mol^–1

1 mole of ammonium nitrate crystals are dissolved in an excess of water, the enthalpy change of solution is found to be +25.4 kJ mol^–1

Was sal ammoniac at one point added to meat curing to drop the meat temperature if there was a warm spell after the farmer began the process of curing?  Could the later inclusion into the curing process originate from this?  This is a fascinating possibility.

Salt Road from Tibet to Nepal

It was the end of my first trip to Nepal.  I found that clues of ancient realities are sometimes closer to the surface than we may think.  I will know it when I see it.  I was looking for any pointer towards or away from my hypothesis.  The picture that is slowly emerging from the evidence is that nitrate salts was traded across China and used to cure meat and as a condiment.

Ayush, from Urban Food, scheduled one last meeting for us with his sales staff at their head office.  Here, we had a brief, but powerful meeting with Dilip Rajbhandari.

I briefly outlined my theory to Mr. Dilip to get his input.  To my surprise, he was intrigued by it and asked if I knew about the salt trade between Tibet and Nepal.  Of course, I did not and he explained it to me.  More than that, he encouraged me to go to an old market in Kathmandu where I would meet salt traders from Tibet.

This small tidbit of information is the kind of pointer I was looking for.  Normal, unforced common knowledge facts which point to either the confirmation or contradiction of my theory.  This one seemed to confirm my suspicion.

Fisher states it very simply that in Tibet, grain was more valuable than salt since they have rich salt deposits, but lacks grain.  In Western Nepal, they have an abundance of grain and no salt.   (Fisher, J. F; 1978)

Stong ties existed since antiquity between Nepal, India, China and the kingdoms surrounding Turpan and Turpan itself.  There was a free flow of scholars (for the large part) and trade in various salts, including and chiefly sal ammoniac.

That night we visited the ancient markets of Kathmandu and we tasted and talked about salt until late into the night.

Conclusion

I found more evidence of the trade in sal ammoniac than in the trade with saltpeter early on in the Christian era.  It is safe to assume that this was the case for hundreds, if not thousands of years before written records started keeping record of and describing these.

Technically sal ammonia fits the profile as a good meat curing agent and good documentary evidence support the notion that it was used as such before saltpeter became more widely available by industrial demands.

It seems unlikely that meat curing started in India and it leaves the Turpan area as still the candidate for this designation with the best credentials.

It is likely that sal ammoniac miners and traders substituted the crystals which they mined from the volcanic mountain in the Turfan area with salt from the basin itself which contained nitrates in the form of sodium nitrate which makes for very poor gunpowder on account of the sodiums high affinity for moisture, but a very good curing agent for meat.

Sal ammonian from Turfan and Tibet probably made its way into Nepal, the eastern and western regions of China and through Samarkand, into the Mediterranean.  Sal Ammoniac was produced in the region of Samarkand also, but the question is if they produced enough since almost everything they produced were exported indicating a strong demand and limited local supply which, I assume, was supplemented with stock from Turfan and Tibet.

The hypothesis that meat curing originates from the Turfan area is undoubtedly supported by this evidence.  The fascinating journey continues!

References

Anderson S. S.. 1880.  The Farmers Guide, published by S. Anderson, Jr. from
Linwood, Delaware Co., Penn

Bhagvat Sinh Jee, H. H., reprint 1998,  History of Hindoo medical science, Logos Press, New Delhi.  A short history of Aryan medical science was first published in 1896

1842.  The Encyclopaedia Britannica Or Dictionary of Arts, Sciences, and General Literature, Volume 18.  Adam and Charles Black, Edinburgh.

Fisher, J. F. (editor).  1978. Himalayan Anthropology: The Indo-Tibetan Interface.  Mouton Publishers.

Frey, J. W..  2009.  The Indian Saltpeter Trade, the Military Revolution, and the Rise of Britain as a Global Superpower; from  The Historian, Vol. 71, No. 3 (FALL 2009), pp. 507-554;  Published by: Wiley Stable URL: http://www.jstor.org/stable/24454667 Accessed: 23-09-2017 12:56 UTC

(Gettysburg Compiler, Gettysburg Pennsylvania, 20 June 1821, p 4)

Hansen, V.  2012.  The Silk Road: A New History.  Oxford University Press.

Hiscox, G. D..  1916.  Henley’s twentieth century formulas, recipes and processes.  The Norman W Henley Publishing Company.

Johnstone, C. I.. 1833.  The Cook and Housewife’s Manual.  Oliver & Boyd.

Letheby, H., Professor of chemistry in the College of London hospital, and medical officer of health and food analyst for the city of London, 1870, ON FOOD, Four Canton lectures delivered before the society for the encouragement of arts, manufactures, and commerce, delivered in 1868.  Longmans, Green and Co, London.

Lodders, K., and Fegley, B. Jr.  2011.  Chemistry of the Solar System.  Royal Society of Chemistry (RSC) Publishing.

Mather, T. A., Allen, A.G., Davison, M., Pyle, D.M., Oppenheimer, C., McGonigle, A.J.S.. 2004.  Nitric acid from volcanoes.  Earth and Planetary Science Letters.  Volume 218, Issues 1–2, 30 January 2004, Pages 17-30

Needham, J.. 1959.  Science and Civilisation in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth.  Cambridge University Press.

Needham, J.. 1980.  Science and Civilisation in China: Volume 5, Chemical and Chemical Technology; Part IV:  SPAGYRICAL DISCOVERY AND INVENTION: APPARATUS, THEORIES AND GIFTS  Cambridge University Press.

Phillips, H. P..  2016.  The History and Chronology of Gunpowder and Gunpowder Weapons (c.1000 to 1850)  Notion Press.

Pliny the Elder, Natural History, Latin Text and Translations.

The Tradesman: Or, Commercial Magazine, Volume 3.  1809.  Sherwood, Neely and Jones.  London.

Turner WES . 1956. Studies in ancient glasses and glassmaking processes. Part V. Raw materials and melting processes. J Soc Glass Technol 40:277T–300T

Yan Qin, Yanhe Li, Huiming Bao, Feng Liu, Kejun Hou, Defang Wan, and Cheng Zhang.  2012.  Massive atmospheric nitrate accumulation in a continental interior desert, northwestern China.  Geology, http://www.gsapubs.org. page 623-626

Ray, P. C., 1902,  A History of Hindu Chemistry from the earliest time to the middle of the sixteenth century A.D..  Williams and Norgate.

Von Humboldt, A.  2011 with original publication in 1850.  Views of Nature: Or Contemplations on the Sublime Phenomena of Creation.  Cambridge University Press.

Wensheng, G. E., MICHALSKI, G.,  Keqin, C. A. I., Fan, W., and Yaran, L. I. U.. 2014. The Characteristics and Genesis of the Massive Nitrate Deposits in the Turpan-Hami Basin of Xinjiang, China. Acta Geologica Sinica (English Edition), 88(supp. 1): 218–219.

Witzel, Michael, “Vedas and Upaniṣads“, in: Flood 2003, p. 69; For oral composition and oral transmission for “many hundreds of years” before being written down, see: Avari 2007, p. 76

https://books.google.co.za/books?id=EG6gsGX3RYkC&pg=PA84&lpg=PA84&dq=%22sal+ammoniac%22,+ham+cure&source=bl&ots=iHMX2Ejh2v&sig=ayDHgm5o2OrC9jZm08ACSQJK508&hl=en&sa=X&ved=0ahUKEwj3qdmBwrnXAhXHI1AKHdDUC24Q6AEIKTAB#v=onepage&q=%22sal%20ammoniac%22%2C%20ham%20cure&f=false

https://archive.org/stream/sinoiranicachine00laufrich#page/508/mode/2up/search/preserve+

Our last day on the Mardi Himal trek Nepal, we stayed over at the Mardi Himal Eco Village Kalimati.

Quintessentially Nepalese, everything about this magical place is organic and natural. They like their fruit and spices fresh and home-grown. Around the homestead where we are to spend the night were various spices and foods set out to dry.

Black cardamon, from the ginger family, is indigenous to the sub Hymalian region.  It is a taste enhancer when cooked with food.  It is used in meat pickles, meat stews, and curries.  It is one of the secret ingredients in the local bacon industry. One of the finds of the trip, I bought a sachet produced by Himalica for Roy Oliver to do his magic with.  Roy is our resident master butcher at Woodys Consumer Brand.

At the entrance to the house is rice.  Rice is dried and stored and before it is used, it is spread for another day in the sun to dry properly.

Upstairs there are small potatoes being dried.

Onions are being dried in one corner.

Local Garlic.

Corn is dried before it is stripped off the carb and ground.

While I am taking photos, Minette and Tristan are trying their hands at carrying the rice crop. 😀

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Upstairs I find these two instruments, commonly used for working the rice fields – hasiya and kutto.

Back in Kathmandu, we walk through the ancient market area of Ason and I buy spices for Roy Oliver. Prashant helps me to identify it and gives guidance on how best to use it.

Prashant, our guide to the market knows the local history well.  He holds a degree in science and his eye for detail serves him well as a tour guide.  We walk the old dusty streets of the ancient city and he steers us through the hustle and bustle to the spice traders and the salt merchants.  Every corner of the city solicits more historical information and background than one can possibly retain in a week and becomes the bedrock of a lifetime of study.

For Roy Oliver, I get round black spice: Timmur, as it is called in Nepal and also called  sichuan pepper.

Prashant suggests we grind it up and use it as a spice in pickles and soups. Mix it with black salt for better taste.  I try some of it and it is an exciting spice with at least three dominant aftertastes.

Next, I choose a green leafy spice: Jimmu

Prashant recommends that one heat some oil in a spoon and put a little jimmu in it and puts it into soup when it is almost black. Best with lentil soup.

I have a special interest in salts and spend a lot of time with the many salt merchants of the market, mostly old ladies.  I choose a bad tasting brown salt.  Kalak namak or Nepalese Black Salt (bire noon), the pungent smell is due to the presence of sulfur.  Prashant recommends,  “simply grind it and use it in pickles and soups. Garnishing curry with powdered black salt will enhance the taste.”  I am intrigued to see the results in Roys’ hands.

Sites and culinary traditions of Nepal are ancient.  In all my travels have I never had the quality of food that we had in Nepal where every housewife and farmer are master chefs!  Here, one finds a depth in the fusion of spices and aromas, probably unlike anywhere else on the planet.   I will return here often in person, in my mind and dreams and by email for advice – this is the spice jewel in the crown of the taste capitals of the world!

(c) eben van tonder, October 2017

Note: This article was written with the help of both Prashant Neupane and Sabin Dhakal.  All mistakes and omissions are due to my own misunderstanding and limited knowledge.  Prashant is employed by Travelines and he arranged out itinerary in Nepal.  Sabin guided us on our trek to the Mardi Himal base camp.

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I researched bacon producers in Nepal when we planned our hiking trip. I came across the Facebook page of Katmandu’s Urban Food. I was immediately struck by the fact that the look of their company reminded me very much about how Woodys was started. It strangely “felt” the same.

The day after our arrival in Katmandu, the young and dynamic CEO and co-founder of Urban Food, Ayush Rajbhandari picked us up from our hotel for a factory visit. It was he who made the booking for us at the Dalai-La Boutique Hotel.

When we walked into the hotel, I told Minette and Tristan that I felt like Omar Sharif walking into a scene in precolonial India – so perfect and authentic is the ambiance. I suddenly felt very old when nobody knew whom Omar Sharif was.

Ayush put us in touch with Deewaker Piya’s Travelines who turns out to be the best tour operator in Nepal and who became the creators of our entire Nepalese adventure and friend.

We drove through the streets of Nepal and we had the privilege to hear how Urban Food was created. A brain child of him and his brothers, the company was created for exactly the same reason as Oscar and I created Woodys, 8 years ago. Natives from Nepal, their father has been a trader all his life and like Oscar and I, they too saw how easily agencies to distribute products in a region are lost. As was the case with Oscar and I, the decision was made to create their own brand, producing their own products and so, own their own destiny.

The concept is simple and brilliant. To provide a network of high quality Nepalese food outlets in the form of a retail outlet and a number of fast-food carts under their brand, supplied from a central factory where quality and innovation are owned and controlled by them.

Looking at the interior and the theme of the Urban Food Fast Food outlet, the strong American influence of the American educated Ayush becomes clear. The set of complete works of Shakespeare in his office gives away the fact that he majored in English in his undergraduate studies in Texas. The Beatles playing in the background, the aroma of exquisite American fast food served with unique Nepalese influences along with traditional dishes blending together to form an winning combination. Many of the dishes being so unique and authentic that the recipes come straight out of their mom’s kitchen.

I sat listening to Ayush enthusiastically recounting the start of their business wile enjoying the most amazing hot dog I ever had in my entire life and realized how privileged we are be with a company who will become legendary in its quality and amazing dishes and grace travel magazines around the world as a “must visit and experience” for travellers to Nepal.

The similarities with the creation of Woodys could not have been more striking than when we visited their factory. Here Ayush and his brother slept in the rooms adjacent to the factory that later became their offices and after work, they would do a 45 minute hike up a hill next to the factory. While setting up Woodys I hiked up Table Mountain sometimes every day and Oscar joined me whenever he was in Cape Town on epic hikes.

At their factory I was again struck by authentic nature of this amazing company. The bacon brines are skillfully blended by hand by their production manager. Two secret ingredients are added which took me by surprise and taught me the valuable lesson of how easily a signature can be created by adding the one extra “secret and totally authentic” ingredient. The amazing staff who worked on a holiday, key to the success of these young entrepreneurs.

We forged a strong bond and set plans in motion that will not only see Ayush visit Woodys in Cape Town and spent a week with us where trials have been planned to continue to learn from each other. Future projects have been agreed upon for Nepal and India which will see a close tie between Urban Food and Woodys Consumer Brands.

On the way back to our hotel we stopped at the famous “monkey temple.” Ayush told us about the Buddhist philosophy of the ebbs and flows in life. How life is a constant flux and challenges we experience now will pass.

My mind was with Woodys and my friends back home. I remembered the day at Woodys when Oscar called the management team together and told us that we only have cash left to trade till the end of the week. He informed us of the measures under way to resolve the challenges and then asked this question. “How do we respond to such challenges?” Yesterday, at this spiritual place I remembered him say, “We respond by doing our work and the different takes of today as best we can and focussing on that and nothing else.” The ebbs and flows of
life will take care of itself.

Gratitude filled me. For the grace to have overcome the past challenges. Faith that we will be able to face any in the future. Oscar as my friend, brother and partner. Will, James, Adriaan, Roy and the Woodys family. The unfathomable opportunities ahead of us. The privilege of being with friends like Ayush and Urban Food and experiencing the birth of another legendary company who not only understand how to produce bacon and exceptional food but also, and even more importantly, the art of living!

Random photos from an amazing day:

Regulations of Nitrate and Nitrite post-1920:  the problem of residual nitrite
By Eben van Tonder
27 August 2017

Also, see Bacon & the Art of Living, Chapter 11.06: Regulations of Nitrate and Nitrite post-1920’s: the problem of residual nitrite

 

INTRODUCTION

I am working in a pork processing plant.  I am not a scientist but I love knowing how things work and have a special love for chemistry.  The health considerations of the use of nitrite and nitrate together in a bacon curing brine are the issue brought about by the fact that it is allowed in South Africa.  I approach the issue from the standpoint of tracking the issues of residual nitrite from a historical perspective.  The entire matter of phenomenally complex and this is at best notes on my personal introduction to the issue.

SUMMARY

In South Africa commercial curing brines are still being sold that contain both nitrates and nitrites.  In Europe and America, this is not allowed.  I examine the historical context and the health concerns that gave rise to limiting residual nitrite since the 1920’s  and following the N-nitrosamine hysteria of the 1970’s, the introduction of ascorbate or erythorbate in nitrite brines and the fact that it was made illegal to use nitrate with nitrite in certain classes of bacon. The matter of preservatives in food is always a balancing act.  On the one hand is the potential negative influence on human health of the preservative and on the other hand are the pathogens that the preservative protects us from.  It will become clear that the exact same is at issue in the consideration of nitrite.  A second important aspect is always that of dosage.  Preservatives, in high dosages, are harmful to human health, but at low dosages are less problematic.  An example is alchol which is allowed in human food and drink even though at high dosages, it is harmful.  Nitrite falls somewhat in this category, but the reality of N-nitrosamine formation warrants a far more comprehensive approach to minimise it in bacon than only limiting the dosage of nitrite (even though this by itself is an important strategy).

SALTPETER (NITRATE)

The story of bacon is the story of nitrate, nitrite and nitric oxide and its ability to preserve meat, imparting a particular cured meat flavour and a characteristic pinkish-reddish cooked-cured meat colour.

The earliest curing agent that imparted these qualities to the meat was nitrate.  The chemical formula for nitrate is  .  It is used as an ingredient in gunpowder, as fertiliser and to cure meat.  It was one of the earliest and most enigmatic salts known from antiquity both in the East and the West.  There is a long line of inquiry to try and determine what gives this amazing compound its unique power.  In the West, some scholars likened it to the character of the triune God himself and in the East, in China, it was seen by some as one of the components of the elixir of immortality.

The metals most generally reacting with nitrate () are the alkali metals, potassium to form saltpeter and sodium to form Chlian saltpeter and sometimes the alkali earth metal, calcium to form calcium nitrate, originally known as Norwegian Saltpeter.  It is most abundantly found naturally in arid regions around the world and it can be made by human action.  By the 1800’s, the technology to produce it was so widespread among German farmers that authors, writing about it, did not even bother to describe the techniques used.

The preserving power of saltpeter is something which I suspect was noticed by ancient civilizations from as early as 5000 BCE.  (Salt – 7000 years of meat-curing)  There is no doubt that these civilizations also noticed its ability to cause meat colour to change from dull brown as it oxidises after slaughter, back to a reddish-pinkish colour and to impart a particular appealing cured meat taste.

It is probable that art of meat curing developed in desert regions in China, probably in the vast Taklimakan Desert in Western China, in the Tarim Bason from where it spread into the heart of Europe.  The nations of Germany, Italy, Spain, Denmark, Holland, England, and Ireland adopted meat curing which was done with salt and a little bit of saltpeter.  In Europe, saltpeter became universal in its inclusion along with salt in meat curing between 1600 and 1750, probably near 1700.  (Lauer K., 1991)

There is evidence to suggest a link between the use of saltpeter and human disease from very early on.  Klaus Lauer (1991) analysed cook books from Germany and Austria between 1540 and 1900 and found some historical parallels between the use of saltpeter in foods and the appearance of colorectal cancer and multiple sclerosis.  Lauder writes,  “According to summarizing works on the history of cancer, large bowel cancer was only seldom reported in the antiquity and Middle-Ages. Its first detailed depictions date from the early 19th century, followed by a rapidly increasing number of reports during the 19th century.”  He notes that “it is of particular interest at what time nitrate or saltpetre was first used in human nutrition,” being at around the same time and increasing as the use of saltpeter in food increased.  (Lauer K., 1991)  There is, however, no record that this was ever noticed at the time.

As alarming as this is, it should be noted that this may prove nothing more than the danger of uncontrolled or highly irregular nitrite levels in meat curing brought about by the use of saltpeter.  Adding nitrate (saltpeter) is, in fact, adding nitrite.  Later we will see that the exact opposite is also true namely that adding only nitrite, is at the same time adding nitrate also since just as bacterial reduction changes nitrates to nitrites, so chemical reactions in the meat matrix change nitrites into nitrates through oxidation.  More about this later.

The people may not have noticed the health impact on the overall population of the use of nitrates, but something that was noticed is the fact that the use of saltpeter in food prevents foodborne toxins.  Kerner in Germany found in a series of studies conducted in 1817, 1820 and 1822 that the outbreaks of sausage poisoning or botulism are linked to the omission of nitrate (saltpeter) in the salt mixture to cure meat for sausage production.    Botulism is an often fatal foodborne disease from the toxins produced by a bacteria, Clostridium Botulinum. (Frences, M. P., et al. 1981)

In a time of superstition and secret remedies, saltpeter was regarded with awe and wonder.  (Saltpeter:  A Concise History and the Discovery of Dr. Ed Polenske)  A newspaper report from 1898 says that saltpeter miners working in a cave has “remarkable health.”  (The Wyandotte Herald, Kansa City, Kansas, 7 April 1898, “Air in Mammoth Cave“)

So, despite the fact that we can look back at the time before 1920, and see that there may have been an impact from the increased use of saltpeter on the general health of the German and Austrian population, and by extension, on the European population, such a link was probably not obvious.  The general view of saltpeter was favourable.

NITRITE

From the late 1800’s, scientists started to work out that the saltpeter was not the real curing agent, but its cousin, the far more toxic compound, nitrite (). It started to emerge that it has a more direct impact on curing than nitrate.  

Contrary to the generally positive view of saltpeter pre-1900’s, nitrite was viewed by the public in the most negative light.  Their view was not completely unfounded because it is estimated that nitrite is 10 times more toxic than nitrate, but what the general public did not understand was that nitrate became nitrite after a time and that the nitrate from their darling of all salts, sodium or potassium nitrate, turned into the villain, nitrite.

Scientists experimented from early on in its direct use in meat curing.  A private laboratory in Germany, founded in 1848 by C.R. Fresenius recorded, for example, experimented with sodium nitrite as curing agent.  (Concerning Chemical Synthesis and Food Additives)  THis is the earliest experiment I have been able to locate thus far where nitrite is used as a preservative in meat.

The Russian botanist and microbiologist, Sergei Nikolaievich Winogradsky (1856 – 1953) identified a class of bacteria which oxidizes ammonia () or ammonium () to nitrite () and nitrite to nitrate ().  The process is called nitrification.

E. Meusel (1875) discovered another class of microorganisms living in soil and natural waters which reduce nitrates to nitrites and even further.  (Meusel, E. 1875)  It was found that in the absence of oxygen, these microbes use and thus reduces nitrates () to nitrite () in their metabolic processes.  In 1790 Antoine de Lavoisier (1743 – 1794) named the compound nitrite “as they are formed by nitric or by nitrous acid.”  (Lavoisier, A; 1965: 217)  Thus two different compounds exist with only a small change in the spelling namely nitrate and nitrite, indicating the fact that nitrite has one less oxygen atom compared to nitrate.  The loss of one oxygen atom, however, renders the molecule far more reactive, increasing its toxicity 10 times.

In 1891, Eduard Polenske, working for the Imperial Health Office, analysed cured meat for its nutritional value and noted that the nitrate in the curing brine and in the meat changed to nitrites.  He predictably and correctly speculated that this was due to microbial activity, identified by Meusel, 16 years earlier.  In his article, he predicted that his the expected reduction would cause an outcry.

Academic work continued uncovering a much closer relationship between the toxic nitrite and meat curing than the darling of the sciences, saltpeter.  The German scientist, Nothwang confirmed the presence of nitrite in curing brines in 1892.  In 1899, another German scientist, K. B. Lehmann confirmed that the cured colour was linked to nitrite and not saltpeter.  Yet another German hygienists, one of Lehmann’s assistant at the Institute of Hygiene in Würzburg,  Karl Kißkalt (1875 – 1962), confirmed Lehmann’s observations and showed that the same red colour resulted if the meat was left in saltpeter (potassium nitrate) for several days before it was cooked, thus confirming Polenske’s notion of bacterial reduction of nitrate to nitrite which finally cures the meat.  S. J. Haldane showed that nitrite is further reduced to nitric oxide (NO) in the presence of muscle myoglobin and forms iron-nitrosyl-myoglobin. It is nitrosylated myoglobin that gives cured meat, including bacon and hot dogs, their distinctive red colour and protects the meat from oxidation and spoiling.

The work of these scientists was enough evidence for the German government and in 1909, probably due to the negative views of the public towards nitrite, they legalised only the use of a partially reduced form of nitrates in curing mixes which were marketed across Europe.  (Bryan, N. S. et al, 2017: 86 – 90)

The Danish invention

The Danes applied their knowledge of bacterial reduction of nitrate to nitrite and developed a curing method where they reused brine that was “reduced” to nitrite already. They allowed fresh brine to be continually introduced into the system, bacterial reduction to take place and thus supplemented the nitrite concentration of the previously used brine.  This had the additional benefit of “seeding” new brine with just the right bacteria required for nitrite reduction.

According to this method they first injected fresh brine consisting of salt and saltpeter (potassium nitrate) into meat.  They then left the meat for several days in a cover brine. The cover brine was never changed and came to be known as the “mother brine.”  It was their source of nitrite that was directly applied to the curing process.  The mother brine was strained and boiled before it was re-used to eliminate pathogenic bacteria.

1910/ 1911

Clues to the date of the Danish invention come to us from newspaper reports about the only independent farmer-owned Pig Factory in Britain of that time, the St. Edmunds Bacon Factory Ltd. in Elmswell.  The factory was set up in 1911. According to the newspaper reports they learned and practiced what at first was known as the Danish method of curing bacon and later became known as tank-curing or Wiltshire cure.  A person was sent from the UK to Denmark in 1910 to learn the new Danish Method.  (elmswell-history.org.uk) This Danish method involved the Danish cooperative method of pork production founded by Peter Bojsen on 14 July 1887 in Horsens.  The newspaper reports talked about a “new Danish” method.  The “new” aspect in 1910 and 1911 was undoubtedly the tank curing method.

Another account from England puts the Danish invention of tank curing early in the 1900’s.  C. & T. Harris from Wiltshire, UK, switched from dry curing to the Danish method during this time. In a private communication between myself and the curator of the Calne Heritage Centre, Susan Boddington, about John Bromham who started working in the Harris factory in 1920 and became assistant to the chief engineer, she writes: “John Bromham wrote his account around 1986, but as he started in the factory in 1920 his memory went back to a time not long after Harris had switched over to this wet cure.”

So, early in the 1900’s, probably sometime between 1899 and 1910, the Danes invented and practiced tank-curing which was brought to England around 1911 based on the work of the fathers of our current method of meat curing.

The German/ Austro-Hungarian invention

Where Denmark focused on harnessing the power of old brine, in Germany they were toying with the idea of using sodium nitrite as their source of nitrite.  Sodium nitrite was at this time used extensively in an intermediary step in the lucrative coal tar dye industry that flourished in Germany and in the Austrian-Hungarian empire, notably around the city of Prague.  There was a second use of sodium nitrite in medicine. It was expensive to produce and viewed with much skepticism by the general public for use in food on account of its high toxicity.  (Concerning the direct addition of nitrite to curing brine)

It was the First World War that provided the transition events that caused the sodium nitrite to end up being used as the source of nitrite in curing brines in Germany where its use in food was still illegal.  Saltpeter was reserved for the war effort being one of the main components used in manufacturing of gunpowder and was consequently no longer available as curing agent for meat during World War One. (Concerning the direct addition of nitrite to curing brine)

1914

In August 1914, the War Raw Materials Department (Kriegsrohstoffabteilung or KRA) was set up under the leadership of Walther Rathenau.  It was Rathenau who was directly responsible for the prohibition on the use of salpeter.  He, therefore, is the person in large part responsible creating the motivation for the meat industry in Germany to change from saltpeter to sodium nitrite as curing medium of choice for the German meat industry during World War One.  (Concerning the direct addition of nitrite to curing brine)

The first country to legalise the use of nitrite directly was the Austro-Hungarian Empire and in 1915.  At age 19, Ladislav Nachmüllner invents Praganda, the first legal commercial curing brine containing sodium nitrite in the city of Prague.  He says that he discovered the power of sodium nitrite through  “modern-day professional and scientific investigation.”  He probably actively sought an application of the work of Haldane. He quotes the exact discovery that Haldane was credited for in 1901 that nitrite interacts with the meat’s “haemoglobin, which changes to red nitro-oxy-haemoglobin.”  (The Naming of Prague Salt)

1917

By 1917 nitrite was not only used for curing meat in Germany, but proprietary meat cures containing nitrites were being marketed across Europe.  (Concerning Chemical Synthesis and Food Additives)

Developments in the United States

Both these methods were being looked at very closely in the United States around this time.

1905

The first recorded direct use of sodium nitrite as a curing agent in the USA was in a secret experiment in 1905.  The USDA approved its use as a food additive in 1906.  (Concerning the direct addition of nitrite to curing brine)

1910

A court case was brought by the US Federal Government against the Mill and Elevator Company of Lexington, Nebraska.  The charge was that they adulterated and misbranded flour and sold it to a grocer in Castle, Missouri.  The case was brought by the government under the pure food and drug act of 1906.  (Chicago Daily Tribune ; 7 July 1910; Page 15) The government contended that “poisonous nitrites are produced in the flour by bleaching.”  This is one example of the gigantic controversy that raged around the world about the use of nitrites in food and the careful work that was done by the US government in the 1920, 30’s and onwards, was in the first place in dealing with the known high toxicity of nitrites.

1915

In 1915, George F. Doran of Omaha, Nebraska, filed a patent for using “sterilized waste pickling liquor which he discovered contains soluble nitrites produced by conversion of the potassium nitrate, sodium nitrate, or other nitrate of the pickling liquor when fresh, into nitrites.  As such his patent involved taking waste pickling liquor from the cured meats.”  This is the same concept as tank curing invented in Denmark sometime before 1910 and probably after 1899. He states the objective of his invention as “to produce in a convenient and more rapid manner a complete cure of packing house meats; to increase the efficiency of the meat-curing art; to produce a milder cure; and to produce a better product from a physiological standpoint.” (US 1259376 A)

Despite the obvious advantage of a far quicker curing time of the use of sodium nitrite had over the tank cured Danish method, the fact that Doran still took the trouble to register the patent for a tank curing method in 1915 makes sense if one considers that tank-curing or the Wiltshire curing process became widespread in application in England.

The problem with the Danish and later, Engish system was, of course, shelf life due to the high microbial load from the mother brine and the uncontrolled nature of the process of nitrite formation (nitrite levels have been shown to range between 2 and 960 ppm in products cured using this method). (Bryan, N. S. et al, 2017: 86 – 90)

1923

In 1923, the Bureau of Animal Industry commissioned a study to investigate the direct addition of nitrite for meat curing.  Kerr, et al, under the supervision of inspectors from the Bureau of Animal Industry, cured hams with approximately 2000 ppm nitrite in the curing mix.  The first issue they investigated was to compare nitrite curing with nitrate curing from the standpoint of organoleptic equivalence and if excess amounts of nitrite are required for nitrite curing.

They also looked at the amount of nitrite that was left in the meat after sufficient curing took place, thus introducing the concept of residual nitrite.  These they compared with the amount of nitrite that was in the curing brine.  The question was how much nitrite is required to cure meat.  It was known that nitrite is a more powerful toxin than nitrate; it was further known that using nitrate instead of nitrite caused inconsistent nitrite levels in the curing brine and in the meat.  By understanding the amount of nitrites that typically react in the meat to form nitric oxide and to cure the meat and by taking that as the limit of nitrite that can be added directly, one, therefore, minimises the risk of having consumers ingest nitrites.

1925

By 1925 a document was prepared by the Chicago based organisation, The Institute of American Meat Packers and published in December of this year.  The Institute started as an alignment of the meat packing companies set up by Phil Armour, Gustavus Swift, Nelson Morris, Michael Cudahy, Jacob Dold and others with the University of Chicago.  (Concerning the direct addition of nitrite to curing brine)

A newspaper article about the Institute sets its goal, apart from educating meat industry professionals and new recruits, “to find out how to reduce steers to beef and hogs to pork in the quickest, most economical and the most serviceable manner.”   (The Indiana Gazette.  28 March 1924).  In this statement is the clue to the reason of its dominance in the United States where bigger, better and faster was the call to arms for the new world’s industries.

The document is entitled, “Use of Sodium Nitrite in Curing Meats“, and it it is clear that the direct use of nitrites in curing brines has been practiced from earlier than 1925. (Industrial and Engineering Chemistry, December 1925: 1243)

The article begins “The authorization of the use of sodium nitrite in curing meat by the Bureau of Animal Industry on October 19, 1925, through Amendment 4 to B. A. I. Order 211 (revised), gives increased interest to past and current work on the subject.”  Sodium Nitrite curing brines would, therefore, have arrived in the USA, well before 1925.

The rest of the opening paragraph continues to elaborate on the reason for its preference.   “It is now generally accepted that the salpteter added in curing meat must first be reduced to nitrite, probably by bacteria, before becoming available as an agent in producing the desirable red color in the cured product.  This reduction is the first step in the ultimate formation of nitrosohemoglobin, the color principle.  The change of nitrate to nitrite is by no means complete and varies within considerable limits under operating conditions.  Accordingly, the elimination of this step by the direct addition of smaller amounts of nitrite means the use of less agent and a more exact control.”

1926

The 1926 study by Kerr and co-workers, was done long before there was any link established between nitrite and the formation of cancer-causing substances upon frying and ingestion.  This only emerged in the ’70’s.  In 1926, the work was based on the general knowledge of nitrite’s toxicity and the publics very negative perceptions about it.  In the report, they state that public health was the primary motivation behind the study.  (Kerr, et al, 1926 : 543)  The test was a step in the right direction – towards defining and limiting residual nitrite.

I quote from their report.  “The first experiment involving the direct use of nitrite was formally authorized January 19, 1923, as a result of an application by one of the large establishments operating under Federal meat inspection. Before that time other requests for permission to experiment with nitrite had been received but had not been granted. The authorization for the first experiment specified that the whole process was to be conducted under the supervision of bureau inspectors and that after the curing had been completed the meat was to be held subject to laboratory examination and final judgment and would be destroyed if found to contain an excessive quantity of nitrites or if in any way it was unwholesome or unfit for food. This principle was rigidly adhered to throughout the experimental period, no meat being passed for food until its freedom from excessive nitrites had been assured, either by laboratory examination or through definite knowledge from previous examinations, that the amount of nitrite used in the process would not lead to the presence of an excessive quantity of nitrites in the meat. By “excessive^ is meant a quantity of nitrite materially in excess of that which may be expected to be present in similar meats cured by the usual process.”  (Kerr, et al, 1926 : 543)

An interesting side note is the fact that this fixes the date of the first official experiment using nitrites ever conducted in the United States.  There can be little doubt that the large packing plants in Chicago used nitrites directly in meat curing, long before this, at least from 1918, following World War 1.  I have even received reports of the first unofficial experiment of this nature that was done in 1905, presumably also in Chicago.  (Concerning the direct addition of nitrite to curing brine)  The large establishment who applied for the permit would have been one of the following list of packers, the Armour Packing operation, Morris & Company, Cudahy Packing Company, Wilson Packing Plant or Swift Packing.  These four companies, at the time, were some of the largest and most powerful corporations on earth.

“The maximum nitrite content of any part of any nitrite-cured ham [was found to be] 200 parts per million. The hams cured with nitrate in the parallel experiment showed a maximum nitrite content of 45 parts per million.”  (Kerr, et al, 1926 : 543) The conclusion was that “hams and bacon could be successfully cured with sodium nitrite, and that nitrite curing need not involve the presence of as large quantities of nitrite in the product as sometimes are found in nitrate- cured meats.”  (Kerr, et al, 1926 : 545)

Related to the health concerns, the report concluded the following:

1. “The presence of nitrites in cured meats, was already sanctioned by the authoritative interpretation of the meat inspection and pure food and drugs acts sanctioning the use of saltpeter; as shown previously, meats cured with saltpeter and sodium nitrate regularly contain nitrites. (Wiley, H, et al, 1907) (Kerr, et al, 1926 : 550)
2. The residual nitrites found in the nitrite-cured meats were less than are commonly present in nitrate-cured meats.  The maximum quantity of nitrite found in nitrite-cured meats, in particular, was much smaller than the maximum resulting from the use of nitrate.  (Kerr, et al, 1926 : 550)
3. The nitrite-cured meats were also free from the residual nitrate which is commonly present in nitrate-cured meats.  (Kerr, et al, 1926 : 550)
4. On the contrary, the more accurate control of the amount of “nitrite and the elimination of the residual or unconverted nitrate are definite advantages attained by the substitution.  (Kerr, et al, 1926 : 550)

Following further studies, the Bureau set the legal limit for nitrites in finished products at 200 parts per million.  (Bryan, N. S. et al, 2017: 86 – 90)

Conventional wisdom that surfaced in the 1920’s suggested that nitrate and nitrate should continue to be used in combination in curing brines  (Davidson, M. P. et al; 2005:  171) as was the case with the Danish curing method and the mother brine concept of the previous century.  Nitrite gives the immediate quick cure and nitrate acts as a reservoir for future nitrite and therefore prolongs the supply of nitrite and ensures a longer curing action.  This concept remained with the curing industry until the matter of N-nitrosamines came up in the 1960’s and 70’s, but remarkably enough, it still persists in places like South Africa where to this day, using the two in combination is allowed for bacon.

1931

The USDA progressed the ruling on nitrate and nitrites further in 1931 by stating that where both nitrites and nitrates are used, the limit for nitrite is 156 ppm nitrite and 1716 nitrate per 100lb of pumped, cured meat.  (Bryan, N. S. et al, 2017: 86 – 90)

1960’s – N-Nitrosamine

Up to the 1960’s the limit on the ingoing level of nitrites was based on its toxicity.  In the late 1950’s an incident occurred in Norway involving fish meal that would become a health scare rivaled by few in the past.  1960’s researchers noticed that domestic animals fed on a fodder containing fish meal prepared from nitrite preserved herring were dying from liver failure.  Researchers identified a group of compounds called nitrosamines which formed by a chemical reaction between the naturally occurring amines in the fish and sodium nitrite.  Nitrosamines are potent cancer causing agents and their potential presence in human foods became an immediate worry.  An examination of a wide variety of foods treated with nitrites revealed that nitrosamines could indeed form under certain conditions.  Fried bacon, especially when “done to a crisp,” consistently showed the presence of these compounds.  (Schwarcz, J)  In bacon, the issue is not nitrates, but the nitrites which form N-nitrosamines.

This fundamentally sharpened the focus of the work of Kerr and co-workers of the 1920’s in response to the general toxicity of nitrites to the specific issue of N-nitrosamine formation.  Reviews from 1986 and 1991 reported that “90% of the more than 300 N-nitroso compounds that have been tested in animal species including higher primates causes cancer, but no known case of human cancer has ever been shown to result from exposure to N-nitroso compounds.”  However, despite this, there is an overwhelming body of indirect evidence that shows that a link exists and “the presence of N-nitroso compounds in food is regarded as an etiological risk factor.   It has been suggested that 35% of all cancers in humans are dietary related and this fact should not surprise us.  (Pegg and Shahidi, 2000)

Studies have been done showing that children who eat more than 12 nitrite-cured hot dogs per month have an increased risk of developing childhood leukemia.  The scientists responsible for the findings themselves cautioned that their findings are preliminary and that much more studies must be done.  It may nevertheless be a good approach for parents to reduce their own intake of such products along with that of their children in cases where intake is high.  (Pegg and Shahidi, 2000)

These studies must be balanced by the fact that an overwhelming amount of data has been emerging since the 1980’s that indicate that N-nitroso compounds are formed in the human body.  What is important is that we keep on doing further research on N-nitrosamines and the possible link to cancer in humans.  Not enough evidence exists to draw final conclusions.

1970 – The response to the N-Nitrosamine scare.

Back to the 1970’s, so grave was the concern of the US Government about the issue that in the early 1970’s they seriously considered a total ban on the use of nitrites in foods. (Pegg and Sahidi, 2000)  The response to the N-nitrosamine issue was to go back to the approach that was implemented following the work of Kerr and co-workers in 1926.

The first response was to eliminate nitrate from almost all curing applications.  The reason for this is to ensure greater control over the curing.  Meat processors continued to use nitrate in their curing brines after 1920 until the 1970’s.  One survey from 1930 reported that 54% of curers in the US still used nitrate in their curing operations.  17% used sodium nitrite and 30% used a combination of nitrate and nitrite.  By 1970, 50% of meat processors still used nitrate in canned, shelf-stable.  In 1974 all processors surveyed discontinued the use of nitrates in these products including in bacon, hams, canned sterile meats, and frankfurters.  One of the reasons given for this change is the concern that nitrate is a precursor for N-nitrosamine formation during processing and after consumption.  (Bryan, N. S. et al, 2017: 86 – 90)

The reason for the omission in bacon, in particular, is exactly the fact that the nitrates will, over time continue to be converted to nitrites which will result in continued higher levels of residual nitrites in the bacon compared to if only nitrite is used.  The N-nitrosamine formation from nitrites is a reaction that can happen in the bacon during frying or in the stomach after it has been ingested.  It will not happen from the more stable nitrates.

It has been discovered that nitrate continues to be present in cured meats.  Just as the view that if nitrate was added, no nitrite is present in the brine as was the thinking in the time before the early and mid-1800’s, in exactly the same way it is wrong to think that by adding nitrite only to meat, that no nitrate is present.  “Moller (1971) found that approximately 20% of the nitrite added to a beef product was converted to nitrate within 2 hours of processing.  Nitrate formation was noted during incubation before thermal processing, whereas after cooking only slight nitrate formation was detected.  Upon storage, the conversion of nitrite to nitrate continued.  Herring (1973) found a conspicuous level of nitrate in bacon formulated only from nitrite.  As greater concentrations of nitrite were added to the belly, a higher content of nitrate was detected in the finished product.  They reported that 30% of the nitrite added to bacon was converted to nitrate in less than one week and the level of nitrate continued to increase to approximately 40% of the added nitrite until about 10 weeks of storage.  Moller (1974) suggested that when nitrite is added to meat, a simultaneous oxidation of nitrite to nitrate and the ferrous ion of   to the ferric ion of metMb occurs.” Adding ascorbate or erythorbate plays a key role in this conversion.  (Pegg and Shahidi, 2000)  The issue is not the nitrate itself, but the uncontrolled curing that results from nitrate and the higher residual nitrites.

Secondly, the levels of ingoing nitrite were reduced, especially for bacon.  The efficacy of these measures stems from the fact that the rate of N-nitrosamine formation depends on the square of the concentration of residual nitrites in meats and by reducing the ingoing nitrite, the residual nitrite is automatically reduced and therefore the amount of N-nitrosamines.  (Pegg and Sahidi, 2000)  Legal limits were updated in 1970 in response to the nitrosamine paranoia.  A problem with this approach is however that no matter by how much the ingoing nitrite is reduced, the precursors of N-Nitrosamine still remains in the meat being nitrites, amines, and amino acids.

An N-nitrosamine blocking agent was introduced in the form of sodium ascorbate or erythorbate. “There are several scavengers of nitrite which aid in suppressing N-nitrosation; ascorbic acid, sodium ascorbate and erythorbate have been the preferred compound to date.  Ascorbic acid inhibits N-Nitrosamine formation by reducing   to give dehydroascorbic acid and NO.  Because ascorbic acid competes with amines for, N-Nitrosamine formation is reduced.  Ascorbate reacts with nitrite 240 times more rapidly than ascorbic acid and is, therefore, the preferred candidate of the two.  (Pegg and Sahidi, 2000)

More detailed studies identified the following factors to influence the level of N-nitrosamine formation in cured meats.  Residual and ingoing nitrite levels, preprocessing procedure and conditions, smoking, method of cooking, temperature and time, lean-to-adipose tissue ratio and the presence of catalyst and/ or inhibitors.  It must be noted that in general, levels of N-nitrosamines formation has been minuscule small, in the billions of parts per million and sporadic.  The one recurring problem item remained fried bacon.  In its raw state bacon is generally free from N-nitrosamines “but after high-heat frying, N-nitrosamines are found almost invariably.”  One report found that “all fried bacon samples and cooked-out bacon fats analyzed” were positive for N-nitrosamines although at reduced levels from earlier studies.  (Pegg and Sahidi, 2000)

Regulatory efforts since 1920 have shown a marked decrease in the level of N-nitrosamines in cured meats, even though it is still not possible to eliminate it completely.  “Cassens (1995) reported a marked decrease (approx 80%) in residual nitrite levels in of US prepared cured meat products from those determined 20 years earlier; levels in current retail products were 7 mg/kg from bacon.”  This and similar results have been attributed to lower nitrite addition levels and the increased use of ascorbate or erythorbate.  (Pegg and Sahidi, 2000)

Current USA regulations and tightening the measures from the 1970’s.

Nitrite can be used in foods and nitrate, very selectively based on the product category and the method of curing.  Immersion cured, massaged or pumped products (example hams or pastrami) – maximum ingoing level of 200 ppm sodium or potassium nitrite and/ or 700 ppm nitrate based on raw product weight.  (Bryan, N. S. et al, 2017: 86 – 90)

Dry cured products – a maximum of 625 ppm ingoing nitrite, and/ or 2187 ppm nitrate since the products have long curing times that result in immediate nitrite reaction with myoglobin and longer term conversion of nitrate to nitrite.  (Bryan, N. S. et al, 2017: 86 – 90)

Comminuted products such as Frankfurters, Bologna, and other cured sausages – maximum ingoing nitrite level of 156 ppm sodium or potassium nitrite based on raw meat block.  Nitrite can be added to all these at a rate of 1718 ppm regardless of salt used.  (Bryan, N. S. et al, 2017: 86 – 90)

1978 bacon levels – USA

Inoing nitrite levels were reduced in 1978 and a required limit was set for ascorbate.  It was also explicitly ruled that nitrate may not be used in bacon production.

-Maximum ingoing level of sodium nitrite – 120 ppm

-Maximum ingoing level of potassium nitrite – 148 ppm

-547 ppm ascorbate or erythorbate must be added.

(Bryan, N. S. et al, 2017: 86 – 90)

1980

In the USA, in 1980, the National Acadamy of Sciences (NSA) entered into a contract with the USDA and FDA.  They established the Committee on Nitrate and Alternative Curing Agents in Food.  The brief of the committee was to investigate the health risk associated with the overall exposure to nitrate, nitrite and N-nitroso compounds.  They published a report, “The Health Effects of Nitrite and N-nitroso Compounds.”

They found nitrate not to be carcinogenic or mutagenic.  It was found that certain populations showed an association of an exposure to high nitrate levels and certain cancers.  More studies are required.

Nitrite was similarly found not to act directly as a carcinogen in animal studies and more studies are necessary.

The committee recognised the use of nitrite as an effective barrier against foodborne botulism, thus validating the continued use of nitrites in meat curing.  They also put the overall risk in perspective by estimating the lifetime risk of cancer from cured meats to be one in a million if “humans were exposed to a daily dose of 5.8 to 19 ng of nitrosodimethylamine per ki~ogram of body weight or 0.85 to 2. 7 ng of nitrosodimet~lamine per em of body surface. In arriving at this estimate, the committee has also assumed that (1) the dietary doses given to rats can be converted to unit of dose per unit of body weight or per unit of body surface area to reflect human exposure and (2) that nitrosodimethylamine is the main source of exposure to nitrosamine& for humans and is, therefore, representative of all nitrosamine&, even though its potency in animals is greater than that of many other nitrosamine.”

“The committee also examined seven pothetical population groups and estimated that the lifetime risk of cancer from exposure to all sources of nitrosamines would be 820 to 18,000 per million for a high risk group (including occupational exposure), 11 to 250 in a million for a high cured meat diet group, 8 to 180 in a million for an average population of nonsmokers, and 3 to 74 in a million for a low risk group.”

A specific recommendation, relevant to the question of the use of nitrates in curing brines is that the use of nitrates in curing systems should be eliminated with the exception of products where a long curing time is required.  The reason is that nitrate and nitrates can have acute toxic effects and contribute to the formation of N-nitrose compounds.

Despite all this, the committee found that the prudent approach is to continue to use nitrite as a proven and effective hurdle to prevent the outgrowth of Clostridium Botulinum spores and the accompanying toxin formation.  It is in the publics interest to assume that temperature and other product abuses will take place and using nitrite as a hurdle remains a reasonable measure.

Here is the pdf copy of the entire report:  The Health Effects of Nitrite and N-nitroso Compounds

New 1986 bacon levels – USA – testing the limits of the system

The general trend of reducing residual nitrate and limiting N-nitrosamine formation continued.  The danger, however, exists that ingoing nitrite levels may be reduced so dramatically as to compromise its function as a barrier against botulism.  The danger of nitrites and its benefits must always be held in balance.

-Skinless bacon – the requirements were kept at the 1978 levels, but it was explicitly emphasised that these ruling applies in order to reduce the possibility of N-nitrosamine formation.  A practical measure was introduced which allows for an approximately 20% variance is allowed from the ingoing nitrite on injection or massaging (96-144 ppm).

In order to ensure efficacy against pathogens, sodium nitrite can be reduced to 100 ppm (123 ppm potassium nitrite) with “appropriate partial quality control program.”  If sugar and a starter culture are added to the brine, 40 – 80 ppm sodium nitrite (49 – 99 potassium nitrite).

Dry cured bacon – the limit was set at 200 ppm nitrite or 246 potassium nitrite.

(Bryan, N. S. et al, 2017: 86 – 90)

EU Rules, Directive 95/2/EC, modified in Directive 2006/52/EC

Maximum ingoing level of bacon is 150 ppm nitrite; max residue level at between 50 and 175 ppm. (in Denmark, this limit is lower at 60 – 150 ppm for semi preserved products and special cured hams).  (Bryan, N. S. et al, 2017: 86 – 90)

Canadian Regulations Bacon

120 ppm and it is stated that this level is set in order to prevent N-Nitrosamine formation.  (Bryan, N. S. et al, 2017: 86 – 90)

South African Regulations

The South African max allowed limits on nitrite, nitrate and ascorbate or erythorbate are:

from Regulation R965 of 1977(18):

– Potassium and sodium nitrate:  200mg/ kg
– Potassium or sodium nitrite: 160mg/kg

Where nitrate and nitrite are used in combination they must be added together and proportionally neither one can exceed the max limit (section 2b of Regulation R965 of 1977).

For using erythrobic acid or sodium erythrobate:  550 mg/kg
L Ascorbic Acid:  550 mg/kg.

CONCLUSION

The continued use of nitrite is undoubtedly valid in the face of its efficacy against serious foodborne pathogens.  It is, however, important to take every precaution possible to mitigate the risk posed by N-nitrosamines, including limiting the maximum allowed addition of nitrite to curing brines, limiting residual nitrite, controlling the curing by using nitrites and not nitrates in bacon and the addition of correct levels of ascorbate or erythorbate.  The fact that nitrates are still allowed with nitrites in curing brines in South Africa is a matter of concern.

Objections are two fold.  On the one hand, it increases the residual nitrites (over time, nitrites continue to be formed from nitrates through bacterial reduction) increasing the amount of nitrites present during frying and ingested which can form N-nitrosamines in the stomach.  Another issue is that the exact dosage of nitrites is not left, in part, to the action of bacteria and I fail to see the point behind this.  The thinking about nitrates acting as a reservoir for continued nitrite production in order to maximise its antimicrobial efficacy becomes an irrelevant point in light of the danger of N-nitrosamine formation from the higher residual nitrites and the thinking which stems from the 1920’s has been altered around the world with good reason and yielding good results.

An equally serious problem may be that the South African regulations do not make the use of ascorbate or erythorbate mandatory nor does it set minimum required levels.  It will be interesting to do a study of the residual nitrite levels in South African bacon over time.  Much work remains.

After I did the article, it occurred to me that if I would cut out cured meat from my diet altogether in order to prevent even the smallest chance of exposure to N-nitrosamines and if I would subject the rest of my diet to the same rigor applied to the issue of nitrites, it may very well be found that I was better off eating the processed foods in comparison with what I may consume in its place.  As a whole, it is possible that consuming processed foods along with regular exercises places me in a better position health wise than cutting out these foods from my diet altogether and no exercise.  This issue must be seen in context.  This is a fact that researchers regularly point to when they publish date on the health effects of nitrite.  I can only echo the prevailing sentiment on the subject – that much more research needs to be done.

Few issues received more comprehensive treatment than the matter of N-nitrosamine formation since the early 70’s and an unfathomable amount of excellent literature exists on the subject.  I write these articles in order to learn.  Like the issue of meat curing itself, the matter at hand is very complex.

References:

Bryan, N. S. and Loscalzo, J. (Editors) 2017.  Nitrite and Nitrate in Human Health and Disease.  Springer International Publishing.  Chapter by J. T. Keeton.  jkeeton@tamu.edu

Frances, M. P. (Editor) et al..  1981.  The Health Effects of Nitrate, Nitrite, and N- Nitroso Compounds.  National Academic Press. (https://books.google.co.za/books?id=QkorAAAAYAAJ&printsec=frontcover#v=onepage&q&f=false)

KERR, R. H., MARSH, C. T. N., SCHROEDER, W. F., and BOYER, E. A..  1926.   Associate Chemists, Bureau of Animal Industry, United States Department of Agriculture.  THE USE OF SODIUM NITRITE IN THE CURING OF MEAT.  Journal of Agricultural Research Vol. 33, No. 6.  Sept. 15, 1926 Key No. A-112.  Washington, D. C.

Lauer K. 1991.  The history of nitrite in human nutrition: a contribution from German cookery books.  Journal of clinical epidemiology. 1991;44(3):261-4.

Lavoisier, A.  1965.  Elements of Chemistry.  Dover Publications, Inc.  A republication of a 1790 publication

Morton, I. D. and Lenges. J.  1992.  Education and Training in Food Science: A Changing Scene.  Ellis Hornwood Limited.

Schwarcz, J http://blogs.mcgill.ca/oss/2013/01/04/what-is-saltpeter-used-for-and-is-it-true-it-reduces-certain-%E2%80%9Ccarnal-urges%E2%80%9D/

WILEY, H. W., DUNLAP, F. L., and MCCABE, G. P. 1907. DYES, CHEMICALS, AND PRESERVATIVES IN FOODS. U. S. Dept. Agr., Off. Sec. Food Insp. Decis. 76, 13 p.

The Wyandott Herald, Kansa City, Kansas, 7 April 1898, “Air in Mammoth Cave“